Interrupt List, part 5 of 8

Interrupt List, part 5 of 8
This compilation is Copyright (c) 1989,1990,1991,1992 Ralf Brown
----------2F---------------------------------
INT 2F - Multiplex - NOTES
AH = identifier of program which is to handle the interrupt
00h-7Fh reserved for DOS
B8h-BFh reserved for networks
C0h-FFh reserved for applications
AL is the function code
This is a general mechanism for verifying the presence of a TSR and
communicating with it. When searching for a free identifier code for AH
using the installation check (AL=00h), the calling program should set
BX/CX/DX to 0000h and must not depend on any registers other than CS:IP
and SS:SP to be valid on return, since numerous programs now use additional
registers on input and/or output for the installation check.
Note: Since the multiplex chain is growing so long, and beginning to
experience multiplex number collisions, I am proposing an alternate
multiplex interrupt on INT 2D. If you decide to use the alternate
multiplex, please let me know.
SeeAlso: INT 2D
----------2F---------------------------------
INT 2F - BMB Compuscience Canada Utilities Interface
AH = xx (dynamically assigned based upon a search for a multiplex
number which doesn't answer installed)
AL = 00h installation check
ES:DI = EBEBh:BEBEh
Return: AL = 00h not installed
01h not installed, not OK to install
FFh installed; if ES:DI was EBEBh:BEBEh on entry, ES:DI will point
to a string of the form 'MMMMPPPPPPPPvNNNN' where MMMM is a
short form of the manufacturer's name, PPPPPPPP is a product
name and NNNN is the product's version number
----------2F---------------------------------
INT 2F - Ross Wentworth's Turbo Pascal POPUP LIBRARY
AH = programmer-selected multiplex number
AL = function
00h installation check
Return: AL = FFh if installed
01h get TSR interrupt vectors
Return: DX:AX -> vector table (see below)
02h get TSR code segment
Return: AX = code segment for all interrupt handlers
03h call user exit routine and release TSR's memory
04h get signature string
Return: DX:AX -> counted string containing signature
05h get TSR's INT 2F handler
Return: DX:AX -> INT 2F handler
06h enable/disable TSR
BL = new state (00h disabled, 01h enabled)
07h activate TSR (popup if not disabled)
08h get hotkeys
BL = which hotkey (00h = hotkey 1, 01h = hotkey 2)
Return: AX = hotkey (AH = keyflags, AL = scancode)
09h set hotkey
BL = which hotkey (00h = hotkey 1, 01h = hotkey 2)
CX = new hotkey (CH = keyflags, CL = scancode)
0Ah-1Fh reserved

Format of vector table entry:
Offset Size Description
00h BYTE vector number (00h = end of table)
01h DWORD original vector
05h WORD offset of interrupt handler in TSR's code segment
----------2F---------------------------------
INT 2F - CiriSOFT Spanish University of Valladolid TSR's Interface
AH = xx (dynamically assigned based upon a search for a multiplex
number from C0h to FFh which doesn't answer installed)
AL = 00h installation check
ES:DI = 1492h:1992h
Return: AL = 00h not installed
01h not installed, not OK to install
FFh installed; and if ES:DI was 1492h:1992h on entry, ES:DI will
point to author_name_ver table (see below)
AH = FFh
Note: this interface permits advanced communication with TSRs: it is possible
to make a generic unistall utility, advanced TSR relocator programs
in order to fit fragmented memory areas, etc.
See also: INT 2D"AMIS",INT 2F"Compuscience"

Format of author_name_ver table:
Offset Size Description
-16 WORD segment in which really begins the TSR code (CS in programs
with PSP, XMS upper memory segment if installed as UMB...)
-14 WORD offset in which really begins the TSR code (frecuently 100h
in *.COM programs and 0 in upper memory TSR's).
-12 WORD memory used by TSR (in paragraphs). Knowing the memory area
used by TSR is possible to determine if hooked vectors are
still pointing it (and if it is safe the unistall process).
-10 BYTE characteristics byte
bits 0-2: 000 normal program (with PSP)
001 upper XMS memory block (needed HIMEM.SYS function
to free memory when unistalling)
010 device driver (*.SYS)
011 device driver in EXE format
1xx others (reserved)
bits 3-6 reserved
bit 7 set if extra_table defined and supported
-9 BYTE number of multiplex entry used (redefinition available). Note
that the TSR must be use THIS variable in it's INT 2Fh handler.
-8 WORD offset to vector_area table (see bellow)
-6 WORD offset to extra_area table (see bit 7 in offset -10 and bellow)
-4 4 BYTEs "*##*" (to insure that the TSR verify this agreement)
00h var "AUTHOR:PROGRAM_NAME:VERSION",0 (variable length, this area
is used in order to determine if the TSR is already resident
and it's version code; the ':' char is used as delimiter)

Format of vector_area table:
Offset Size Description
-1 BYTE number of vectors intercepted by TSR
00h BYTE first vector number
01h DWORD first vector pointer before installing the TSR
05h BYTE second vector number
06h DWORD second vector pointer before installing the TSR
. . (and so on) Note that the TSR must be use THIS variables to
invoke previous interrupt handler routines.

Format of extra_area table (needed only to improve relocation feature):
Offset Size Description
00h WORD offset to external_ctrl table (0 if not supported)
02h WORD reserved for future use (0)

Format of external_ctrl table:
Offset Size Description
00h BYTE bit 0: TSR is relocatable (no absolute segment references)
01h WORD offset to a variable which can activate/inhibit the TSR
---And if bit 0 in offset 00h is off:
03h DWORD pointer to ASCIIZ with pathname to executable file which
supports /SR parameter (silent installation & inhibit)
07h DWORD pointer to first variable to initialize on the copy reloaded
from the previous TSR still resident
0Bh DWORD pointer to last variable (all variables packed in one block)
----------2F00-------------------------------
INT 2F U - DOS 2.x PRINT.COM - ???
AH = 00h
???
Return: ???
Notes: DOS 2.x PRINT.COM does not chain to previous INT 2F handler
values in AH other than 00h or 01h cause PRINT to return the number of
files in the queue in AH
SeeAlso: AH=01h
----------2F0080-----------------------------
INT 2F - DOS 3.1+ PRINT.COM - GIVE PRINT A TIME SLICE
AX = 0080h
Return: after PRINT executes
----------2F01-------------------------------
INT 2F U - DOS 2.x PRINT.COM - ???
AH = 01h
???
Return: ???
Notes: DOS 2.x PRINT.COM does not chain to previous INT 2F handler
values in AH other than 00h or 01h cause PRINT to return the number of
files in the queue in AH
SeeAlso: AH=00h
----------2F0100-----------------------------
INT 2F - DOS 3+ PRINT.COM - INSTALLATION CHECK
AX = 0100h
Return: AL = status
00h not installed
01h not installed, but not OK to install
FFh installed
SeeAlso: AX=0101h
----------2F0101-----------------------------
INT 2F - DOS 3+ PRINT.COM - SUBMIT FILE FOR PRINTING
AX = 0101h
DS:DX -> submit packet (see below)
Return: CF clear if successful
AL = 01h added to queue
9Eh now printing
CF set on error
AX = error code (see also INT 21/AH=59h)
01h invalid function
02h file not found
03h path not found
04h out of file handles
05h access denied
08h print queue full
09h spooler busy
0Ch name too long
0Fh invalid drive
SeeAlso: AX=0102h

Format of submit packet:
Offset Size Description
00h BYTE level (must be 00h)
01h DWORD pointer to ASCIZ filename (no wildcards)
----------2F0102-----------------------------
INT 2F - DOS 3+ PRINT.COM - REMOVE FILE FROM PRINT QUEUE
AX = 0102h
DS:DX -> ASCIZ filename (wildcards allowed)
Return: CF clear if successful
CF set on error
AX = error code (see AX=0101h)
SeeAlso: AX=0101h,AX=0103h
----------2F0103-----------------------------
INT 2F - DOS 3+ PRINT.COM - CANCEL ALL FILES IN PRINT QUEUE
AX = 0103h
Return: CF clear if successful
CF set on error
AX = error code (see AX=0101h)
SeeAlso: AX=0102h
----------2F0104-----------------------------
INT 2F - DOS 3+ PRINT.COM - FREEZE PRINT QUEUE TO READ JOB STATUS
AX = 0104h
Return: CF clear if successful
DX = error count
DS:SI -> print queue
CF set on error
AX = error code (see AX=0101h)
Notes: the print queue is an array of 64-byte ASCIZ filenames terminated by
an empty filename; the first name is the file currently being printed
printing is stopped until AX=0105h is called to prevent the queue
from changing while the filenames are being read
SeeAlso: AX=0101h,AX=0105h
----------2F0105-----------------------------
INT 2F - DOS 3+ PRINT.COM - RESTART PRINT QUEUE AFTER STATUS READ
AX = 0105h
Return: CF clear if successful
CF set on error
AX = error code (see AX=0101h)
SeeAlso: AX=0104h
----------2F0106-----------------------------
INT 2F - DOS 3.3+ PRINT.COM - GET PRINTER DEVICE
AX = 0106h
Return: CF set if files in print queue
AX = error code 0008h (queue full)
DS:SI -> device driver header
CF clear if print queue empty
AX = 0000h
Note: documented for DOS 5+, but not documented for prior versions
SeeAlso: AX=0104h
----------2F0200-----------------------------
INT 2F U - PC LAN PROGRAM REDIR/REDIRIFS internal - INSTALLATION CHECK
AX = 0200h
Return: AL = FFh if installed
----------2F0201-----------------------------
INT 2F U - PC LAN PROGRAM REDIR/REDIRIFS internal - ???
AX = 0201h
Return: nothing???
Notes: called by DOS 3.3+ PRINT.COM
AX=0202h appears to be the opposite function
SeeAlso: AX=0202h
----------2F0202-----------------------------
INT 2F U - PC LAN PROGRAM REDIR/REDIRIFS internal - ???
AX = 0202h
???
Return: nothing???
Note: called by DOS 3.3+ PRINT.COM
SeeAlso: AX=0201h
----------2F0203-----------------------------
INT 2F U - PC LAN PROGRAM REDIR/REDIRIFS internal - ???
AX = 0203h
Return: nothing???
Notes: called by DOS 3.3+ PRINT.COM
AX=0204h appears to be the opposite function
SeeAlso: AX=0204h
----------2F0204-----------------------------
INT 2F U - PC LAN PROGRAM REDIR/REDIRIFS internal - ???
AX = 0204h
???
Return: nothing???
Note: called by DOS 3.3 PRINT.COM
----------2F---------------------------------
INT 2F U - PC LAN PROGRAM REDIR/REDIRIFS internal - ???
AX = 02xxh
???
Return: ???
----------2F0500-----------------------------
INT 2F U - DOS 3+ CRITICAL ERROR HANDLER - INSTALLATION CHECK
AX = 0500h
Return: AL = 00h not installed, OK to install
01h not installed, can't install
FFh installed
Note: this set of functions allows a user program to partially or completely
override the default critical error handler's message in COMMAND.COM
SeeAlso: AH=05h,INT 24
----------2F05-------------------------------
INT 2F U - DOS 3+ CRITICAL ERROR HANDLER - EXPAND ERROR INTO STRING
AH = 05h
---DOS 3.x---
AL = extended error code (not zero)
---DOS 4+ ---
AL = error type
01h DOS extended error code
02h parameter error
BX = error code
Return: CF clear if successful
ES:DI -> ASCIZ error message (read-only)
AL = ???
CF set if error code can't be converted to string
Notes: called at start of COMMAND.COM's default critical error handler if
installed by a user program, allowing partial or complete overriding
of the default error message
subfunction 02h called by many DOS 4 external programs
SeeAlso: AX=122Eh,INT 24
----------2F0600-----------------------------
INT 2F - DOS 3+ ASSIGN - INSTALLATION CHECK
AX = 0600h
Return: AL = status
00h not installed
01h not installed, but not OK to install
FFh installed
Notes: ASSIGN is not a TSR in DR-DOS 5.0; it is internally replaced by SUBST
(see INT 21/AH=52h)
undocumented prior to the release of DOS 5.0
SeeAlso: AX=0601h,INT 21/AH=52h
----------2F0601-----------------------------
INT 2F U - DOS 3+ ASSIGN - GET DRIVE ASSIGNMENT TABLE
AX = 0601h
Return: ES = segment of ASSIGN work area and assignment table
Note: under DOS 3+, the 26 bytes starting at ES:0103h specify which drive
each of A: to Z: is mapped to. Initially set to 01h 02h 03h....
SeeAlso: AX=0600h
----------2F0800-----------------------------
INT 2F U - DRIVER.SYS support - INSTALLATION CHECK
AX = 0800h
Return: AL = 00h not installed, OK to install
01h not installed, not OK to install
FFh installed
Note: supported by DR-DOS 5.0
----------2F0801-----------------------------
INT 2F U - DRIVER.SYS support - ADD NEW BLOCK DEVICE
AX = 0801h
DS:DI -> drive data table (see AX=0803h)
Notes: moves down internal list of drive data tables, copying and modifying
the drive description flags word for tables referencing same physical
drive
data table appended to chain of tables
supported by DR-DOS 5.0
SeeAlso: AX=0803h
----------2F0802-----------------------------
INT 2F U - DRIVER.SYS support - EXECUTE DEVICE DRIVER REQUEST
AX = 0802h
ES:BX -> device driver request header (see below)
Return: request header updated as per requested operation
Notes: supported by DR-DOS 5.0
DOS 3.2 executes this function on any AL value from 02h through F7h
SeeAlso: AX=0800h,AX=0801h,AX=0803h,INT 21/AH=52h,INT 21/AH=99h,INT 21/AH=9Ah

Values for command code:
00h INIT
01h MEDIA CHECK (block devices)
02h BUILD BPB (block devices)
03h IOCTL INPUT
04h INPUT
05h NONDESTRUCTIVE INPUT, NO WAIT (character devices)
06h INPUT STATUS (character devices)
07h INPUT FLUSH (character devices)
08h OUTPUT
09h OUTPUT WITH VERIFY
0Ah OUTPUT STATUS (character devices)
0Bh OUTPUT FLUSH (character devices)
0Ch IOCTL OUTPUT
0Dh (DOS 3+) DEVICE OPEN
0Eh (DOS 3+) DEVICE CLOSE
0Fh (DOS 3+) REMOVABLE MEDIA (block devices)
10h (DOS 3+) OUTPUT UNTIL BUSY (character devices)
11h (European MSDOS 4.0) STOP OUTPUT (console screen drivers only)
12h (European MSDOS 4.0) RESTART OUTPUT (console screen drivers only)
13h (DOS 3.2+) GENERIC IOCTL
14h unused
15h (European MSDOS 4.0) RESET UNCERTAIN MEDIA FLAG
16h unused
17h (DOS 3.2+) GET LOGICAL DEVICE
18h (DOS 3.2+) SET LOGICAL DEVICE
19h (DOS 5.0+) CHECK GENERIC IOCTL SUPPORT
80h (CD-ROM) READ LONG
81h (CD-ROM) reserved
82h (CD-ROM) READ LONG PREFETCH
83h (CD-ROM) SEEK
84h (CD-ROM) PLAY AUDIO
85h (CD-ROM) STOP AUDIO
86h (CD-ROM) WRITE LONG
87h (CD-ROM) WRITE LONG VERIFY
88h (CD-ROM) RESUME AUDIO

Format of device driver request header:
Offset Size Description
00h BYTE length of request header
01h BYTE subunit within device driver
02h BYTE command code (see above)
03h WORD status (filled in by device driver)
bit 15: error
bits 14-11: reserved
bit 10: ??? set by DOS kernel on entry to some driver calls
bit 9: busy
bit 8: done (may be clear on return under European MSDOS 4.0)
bits 7-0: error code if bit 15 set (see below)
---DOS---
05h 4 BYTEs reserved (unused in DOS 2.x and 3.x)
09h DWORD (European MSDOS 4.0 only) pointer to next request header in
device's request queue
(other versions) reserved (unused in DOS 2.x and 3.x)
---STARLITE architecture---
05h DWORD pointer to next request header
09h 4 BYTEs reserved
---command code 00h---
0Dh BYTE (return) number of units
0Eh DWORD (call) pointer to DOS device helper function (see below)
(European MSDOS 4.0 only)
(call) pointer past end of memory available to driver (DOS 5.0)
(return) address of first free byte following driver
12h DWORD (call) pointer to commandline arguments
(return) pointer to BPB array (block drivers) or
0000h:0000h (character drivers)
16h BYTE (DOS 3+) drive number for first unit of block driver (0=A)
---European MSDOS 4.0---
17h DWORD pointer to function to save registers on stack
---DOS 5.0---
17h WORD (return) error-message flag
0001h MSDOS should display error msg on init failure
---command code 01h---
0Dh BYTE media descriptor
0Eh BYTE returned status
00h don't know
01h media has not changed
FFh media has been changed
0Fh DWORD (return, DOS 3+) pointer to previous volume ID if OPEN/CLOSE/RM
bit in device header is set and disk changed
---command code 02h---
0Dh BYTE media descriptor
0Eh DWORD transfer address
-> scratch sector if NON-IBM FORMAT bit in device header set
-> first FAT sector otherwise
12h DWORD pointer to BPB (set by driver) (see INT 21/AH=53h)
---command codes 03h,0Ch--- (see also INT 21/AX=4402h,INT 21/AX=4403h)
0Dh BYTE media descriptor (block devices only)
0Eh DWORD transfer address
12h WORD (call) number of bytes to read/write
(return) actual number of bytes read or written
---command codes 04h,08h,09h---
0Dh BYTE media descriptor (block devices only)
0Eh DWORD transfer address
12h WORD byte count (character devices) or sector count (block devices)
14h WORD starting sector number (block devices only)
16h DWORD (DOS 3+) pointer to volume ID if error 0Fh returned
1Ah DWORD (DOS 4+) 32-bit starting sector number (block devices with
device attribute word bit 1 set only) (see INT 21/AH=52h)
---command code 05h---
0Dh BYTE byte read from device if BUSY bit clear on return
---command codes 06h,07h,0Ah,0Bh,0Dh,0Eh,0Fh---
no further fields
---command code 10h---
0Dh BYTE unused
0Eh DWORD transfer address
12h WORD (call) number of bytes to write
(return) actual number of bytes written
---command codes 11h,12h---
0Dh BYTE reserved
---command code 15h---
no further fields
---command codes 13h,19h---
0Dh BYTE category code
00h unknown
01h COMn:
03h CON
05h LPTn:
07h mouse (European MSDOS 4.0)
08h disk
9Eh (STARLITE) Media Access Control driver
0Eh BYTE function code
00h (STARLITE) MAC Bind request
0Fh WORD copy of DS at time of IOCTL call (apparently unused in DOS 3.3)
SI contents (European MSDOS 4.0)
11h WORD offset of device driver header
DI contents (European MSDOS 4.0)
13h DWORD pointer to parameter block from INT 21/AX=440Ch or AX=440Dh
---command codes 80h,82h---
0Dh BYTE addressing mode
00h HSG (default)
01h Phillips/Sony Red Book
0Eh DWORD transfer address (ignored for command 82h)
12h WORD number of sectors to read
(if 0 for command 82h, request is an advisory seek)
14h DWORD starting sector number
logical sector number in HSG mode
frame/second/minute/unused in Red Book mode
(HSG sector = minute * 4500 + second * 75 + frame - 150)
18h BYTE data read mode
00h cooked (2048 bytes per frame)
01h raw (2352 bytes per frame, including EDC/ECC)
19h BYTE interleave size (number of sectors stored consecutively)
1Ah BYTE interleave skip factor (# sectors between consec portions)
---command code 83h---
0Dh BYTE addressing mode (see above)
0Eh DWORD transfer address (ignored)
12h WORD number of sectors to read (ignored)
14h DWORD starting sector number (see also above)
---command code 84h---
0Dh BYTE addressing mode (see above)
0Eh DWORD starting sector number (see also above)
12h DWORD number of sectors to play
---command codes 85h,88h---
no further fields
---command codes 86h,87h---
0Dh BYTE addressing mode (see above)
0Eh DWORD transfer address (ignored in write mode 0)
12h WORD number of sectors to write
14h DWORD starting sector number (see also above)
18h BYTE write mode
00h mode 0 (write all zeros)
01h mode 1 (default) (2048 bytes per sector)
02h mode 2 form 1 (2048 bytes per sector)
03h mode 2 form 2 (2336 bytes per sector)
19h BYTE interleave size (number of sectors stored consecutively)
1Ah BYTE interleave skip factor (# sectors between consec portions)

Values for error code:
00h write-protect violation
01h unknown unit
02h drive not ready
03h unknown command
04h CRC error
05h bad drive request structure length
06h seek error
07h unknown media
08h sector not found
09h printer out of paper
0Ah write fault
0Bh read fault
0Ch general failure
0Dh reserved
0Eh (CD-ROM) media unavailable
0Fh invalid disk change

Call European MSDOS 4.0 device helper function with:
DL = function
00h "SchedClock" called on each timer tick
AL = tick interval in milliseconds
01h "DevDone" device I/O complete
ES:BX -> request header
Note: must update status word first; may be called from
an interrupt handler
02h "PullRequest" pull next request from queue
DS:SI -> DWORD pointer to start of device's request queue
Return: ZF clear if pending request
ES:BX -> request header
ZF set if no more requests
03h "PullParticular" remove specific request from queue
DS:SI -> DWORD pointer to start of device's request queue
ES:BX -> request header
Return: ZF set if request header not found
04h "PushRequest" push the request onto the queue
DS:SI -> DWORD pointer to start of device's request queue
ES:BX -> request header
interrupts disabled
05h "ConsInputFilter" keyboard input check
AX = character (high byte 00h if PC ASCII character)
Return: ZF set if character should be discarded
ZF clear if character should be handled normally
Note: called by keyboard interrupt handler so DOS can scan
for special input characters
06h "SortRequest" push request in sorted order by starting sector
DS:SI -> DWORD pointer to start of device's request queue
ES:BX -> request header
interrupts disabled
07h "SigEvent" send signal on keyboard event
AH = event identifier
Return: AL,FLAGS destroyed
09h "ProcBlock" block on event
AX:BX = event identifier (typically a pointer)
CX = timeout in ms or 0000h for never
DH = interruptible flag (nonzero if pause may be interrupted)
interrupts disabled
Return: after corresponding ProcRun call
CF clear if event wakeup, set if unusual wakeup
ZF set if timeout wakeup, clear if interrupted
AL = wakeup code, nonzero if unusual wakeup
interrupts enabled
BX,CX,DX destroyed
Note: block process and schedules another to run
0Ah "ProcRun" unblock process
AX:BX = event identifier (typically a pointer)
Return: AX = number of processes awakened
ZF set if no processes awakened
BX,CX,DX destroyed
0Bh "QueueInit" initialize/clear character queue
DS:BX -> character queue structure (see below)
Note: the queue size field must be set before calling
0Dh "QueueWrite" put a character in the queue
DS:BX -> character queue (see below)
AL = character to append to end of queue
Return: ZF set if queue is full
ZF clear if character stored
0Eh "QueueRead" get a character from the queue
DS:BX -> character queue (see below)
Return: ZF set if queue is empty
ZF clear if characters in queue
AL = first character in queue
10h "GetDOSVar" return pointer to DOS variable
AL = index of variable
03h current process ID
BX = index into variable if AL specifies an array
CX = expected length of variable
Return: CF clear if successful
DX:AX -> variable
CF set on error
AX,DX destroyed
BX,CX destroyed
Note: the variables may not be modified
14h "Yield" yield CPU if higher-priority task ready to run
Return: FLAGS destroyed
1Bh "CritEnter" begin system critical section
DS:BX -> semaphore (6 BYTEs, initialized to zero)
Return: AX,BX,CX,DX destroyed
1Ch "CritLeave" end system critical section
DS:BX -> semaphore (6 BYTEs, initialized to zero)
Return: AX,BX,CX,DX destroyed
Note: must be called in the context of the process which
called CritEnter on the semaphore
Note: the DWORD pointing at the request queue must be allocated by the driver
and initialized to 0000h:0000h. It always points at the next request
to be executed

Format of character queue:
Offset Size Description
00h WORD size of queue in bytes
02h WORD index of next character out
04h WORD count of characters in the queue
06h N BYTEs queue buffer
----------2F0803-----------------------------
INT 2F U - DOS 4+ DRIVER.SYS support - GET DRIVE DATA TABLE LIST
AX = 0803h
Return: DS:DI -> first drive data table in list
Note: not available under DR-DOS 5.0
SeeAlso: AX=0801h

Format of DOS 3.30 drive data table:
Offset Size Description
00h DWORD pointer to next table
04h BYTE physical unit number (for INT 13)
05h BYTE logical drive number
06h 19 BYTEs BIOS Parameter Block (see also INT 21/AH=53h)
Offset Size Description
00h WORD bytes per sector
02h BYTE sectors per cluster, FFh if unknown
03h WORD number of reserved sectors
05h BYTE number of FATs
06h WORD number of root dir entries
08h WORD total sectors
0Ah BYTE media descriptor, 00h if unknown
0Bh WORD sectors per FAT
0Dh WORD sectors per track
0Fh WORD number of heads
11h WORD number of hidden sectors
19h BYTE flags
bit 6: 16-bit FAT instead of 12-bit FAT
1Ah WORD number of DEVICE OPEN calls without corresponding DEVICE CLOSE
1Ch 11 BYTEs volume label or "NO NAME " if none (always "NO NAME" for
fixed media)
27h BYTE terminating null for volume label???
28h BYTE device type (see INT 21/AX=440Dh)
29h WORD bit flags describing drive
bit 0: fixed media
bit 1: door lock supported
bit 2: ??? (used in determining BPB to set for INT 21/AX=440Dh)
bit 3: all sectors in a track are the same size
bit 4: physical drive has multiple logical units
bit 5: current logical drive for physical drive
bit 6: ???
bit 7: ???
bit 8: ??? (related to disk change detection)
2Bh WORD number of cylinders
2Dh 19 BYTEs BIOS Parameter Block for highest capacity supported
40h 3 BYTEs ???
43h 9 BYTEs filesystem type???, default = "NO NAME "
(apparently only MSDOS 3.30 fixed media, nulls for removable
media and PCDOS 3.30)
4Ch BYTE least-significant byte of last-accessed cylinder number
---removable media---
4Dh DWORD time of last access in clock ticks (FFFFFFFFh if never)
---fixed media---
4Dh WORD partition (FFFFh = primary, 0001h = extended)
4Fh WORD absolute cylinder number of partition's start on physical
drive (always FFFFh if primary partition)

Format of COMPAQ DOS 3.31 drive data table:
Offset Size Description
00h DWORD pointer to next table
04h BYTE physical unit number (for INT 13)
05h BYTE logical drive number
06h 25 BYTEs BIOS Parameter Block (see DOS 4.0-5.0 drive data table below)
1Fh 6 BYTEs ??? apparently always zeros
25h BYTE flags
bit 6: 16-bit FAT instead of 12-bit FAT
5: large volume???
26h WORD device-open count???
28h 11 BYTEs volume label or "NO NAME " if none (always "NO NAME" for
fixed media)
33h BYTE terminating null for volume label
34h BYTE device type (see INT 21/AX=440Dh)
35h WORD bit flags describing drive
37h WORD number of cylinders
39h 25 BYTEs BIOS parameter block for highest capacity drive supports
52h 6 BYTEs ??? apparently always zeros
58h BYTE least-significant byte of last-accessed cylinder number
---removable media---
59h DWORD time of last access in clock ticks (FFFFFFFFh if never)
---fixed media---
59h WORD partition (FFFFh = primary, 0001h = extended)
5Bh WORD absolute cylinder number of partition's start on physical
drive (always FFFFh if primary partition)

Format of DOS 4.0-5.0 drive data table:
Offset Size Description
00h DWORD pointer to next table
04h BYTE physical unit number (for INT 13)
05h BYTE logical drive number
06h 25 BYTEs BIOS Parameter Block (see also INT 21/AH=53h)
Offset Size Description
00h WORD bytes per sector
02h BYTE sectors per cluster, FFh if unknown
03h WORD number of reserved sectors
05h BYTE number of FATs
06h WORD number of root dir entries
08h WORD total sectors (see offset 15h if zero)
0Ah BYTE media descriptor, 00h if unknown
0Bh WORD sectors per FAT
0Dh WORD sectors per track
0Fh WORD number of heads
11h DWORD number of hidden sectors
15h DWORD total sectors if WORD at 08h is zero
1Fh BYTE flags
bit 6: 16-bit FAT instead of 12-bit
20h 2 BYTEs ???
22h BYTE device type (see INT 21/AX=440Dh)
23h WORD bit flags describing drive
bit 0: fixed media
bit 1: door lock supported
bit 2: ???
bit 3: all sectors in a track are the same size
bit 4: physical drive has multiple logical units
bit 5: current logical drive for physical drive
bit 6: ???
bit 7: ???
bit 8: ???
25h WORD number of cylinders
27h 25 BYTEs BIOS Parameter Block for highest capacity supported
40h 7 BYTEs ???
---removable media---
47h DWORD time of last access in clock ticks (FFFFFFFFh if never)
---fixed media, DOS 4.x---
47h WORD partition (FFFFh = primary, 0001h = extended)
49h WORD absolute cylinder number of partition's start on phys drive
(FFFFh if primary partition)
---fixed media, DOS 5.0---
47h WORD ??? apparently always 0001h
49h WORD absolute cylinder number of partition's start on phys drive
------
4Bh 11 BYTEs volume label or "NO NAME " if none (apparently taken from
extended boot record rather than root directory)
56h BYTE terminating null for volume label???
57h DWORD serial number
5Bh 8 BYTEs filesystem type ("FAT12 " or "FAT16 ")
63h BYTE terminating null for filesystem type???
----------2F0C00-----------------------------
INT 2F - AD-DOS - INSTALLATION CHECK
AX = 0C00h
Return: AL = FF if installed
BX = 4144H ('AD')
CX = 2D44H ('-D')
DX = 4F53H ('OS')
Notes: AD-DOS is the DOS version of the After Dark screen blanker for
MS Windows
AH=0Ch is the default multiplex number (there is one report of a
version with AH=C0h as default)
SeeAlso: AX=0C01h
----------2F0C01ES0000-----------------------
INT 2F - AD-DOS - GET RESIDENT CODE SEGMENT
AX = 0C01h
ES = 0000h
Return: CF clear succesful
ES = AD-DOS TSR Code Segment
CF set if failed
SeeAlso: AX=0C00h
----------2F0C02-----------------------------
INT 2F - AD-DOS - CHECK FOR NEW INPUT
AX = 0C02h
Return: BX = status
0000h no input since last check
0001h new input available
Note: this call also resets the new-input flag
----------2F0C03-----------------------------
INT 2F - AD-DOS - SET MINUTES TO WAIT
AX = 0C03h
BX = minutes to wait before blanking screen
CF set
Return: n/a???
Notes: AD-DOS is the DOS version of the After Dark screen blanker
AH=0Ch is the default multiplex number
SeeAlso: AX=0C04h
----------2F0C04-----------------------------
INT 2F - AD-DOS - GET MINUTES TO WAIT
AX = 0C04h
CF set
Return: BX = minutes to wait before blanking screen
???
SeeAlso: AX=0C03h
----------2F0C05-----------------------------
INT 2F - AD-DOS - SET BLANKER STATUS
AX = 0C05h
BX = new state (0000h inactive, 0001h active) (default 0001h)
CF set
Return: n/a???
SeeAlso: AX=0C06h
----------2F0C06-----------------------------
INT 2F - AD-DOS - GET BLANKER STATUS
AX = 0C06h
CF set
Return: BX = current state of screen blanker (0000h inactive, 0001h active)
Note: AD-DOS is the DOS version of the After Dark screen blanker
SeeAlso: AX=0C05h
----------2F0C07-----------------------------
INT 2F - AD-DOS - SET HOT KEY
AX = 0C07h
BX = hot key
CL = hot key shift status
CF set
Return: n/a???
SeeAlso: AX=0C08h
----------2F0C08-----------------------------
INT 2F - AD-DOS - GET CURRENT HOT KEY
AX = 0C08h
CF set
Return: AX = status
0000h successful
BX = Hot Key
CL = Hot Key Shift Status
0008h otherwise
SeeAlso: AX=0C07h
----------2F0C09-----------------------------
INT 2F - AD-DOS - ???
AX = 0C09h
Carry Set
Return: AX = status
0000h successful
???
0009h otherwise
Notes: AD-DOS is the DOS version of the After Dark screen blanker
AH=0Ch is the default multiplex number
----------2F0C0A-----------------------------
INT 2F - AD-DOS - ???
AX = 0C0Ah
CF set
Return: AX = status
0000h successful
BH = ??
BL = ??
000Ah failed
----------2F0C0B-----------------------------
INT 2F - AD-DOS - ???
AX = 0C0Bh
CF set
Return: AX = status
0000h successful
000Bh failed
----------2F0C0C-----------------------------
INT 2F - AD-DOS - SET ??? INTERNAL FLAG TO 01h
AX = 0C0Ch
CF set
Return: AX = status
0000h successful
000Ch failed
Notes: AD-DOS is the DOS version of the After Dark screen blanker
AH=0Ch is the default multiplex number
----------2F0C0E-----------------------------
INT 2F - AD-DOS - SET PASSWORD STATUS
AX = 0C0Eh
BX = new state (0000h disabled, 0001h enabled)
Return: ???
SeeAlso: AX=0C0Fh
----------2F0C0F-----------------------------
INT 2F - AD-DOS - GET PASSWORD STATUS
AX = 0C0Fh
Return: BX = current state (0000h disabled, 0001h enabled)
SeeAlso: AX=0C0Eh
----------2F0C20-----------------------------
INT 2F - AD-DOS - GET AND RESET VxD API STATUS
AX = 0C20h
CF set
Return: AX = status
0000h successful
BX = VxD API Status
0000h no error
0001h error
0100h neither Windows 3.X enhanced mode nor
Windows/386 2.x is running
0200h VM API entry point found
0020h otherwise
Note: this call resets the VxD API Status to zero
SeeAlso: AX=1602h,AX=1607h
----------2F1000-----------------------------
INT 2F - SHARE - INSTALLATION CHECK
AX = 1000h
Return: AL = 00h not installed, OK to install
01h not installed, not OK to install
FFh installed
BUGS: values of AL other than 00h put DOS 3.x SHARE into an infinite loop
(08E9: OR AL,AL
08EB: JNZ 08EB) <- the buggy instruction (DOS 3.3)
values of AL other than described here put PCDOS 4.00 into the same
loop (the buggy instructions are the same)
Notes: supported by OS/2 v1.3+ compatibility box, which always returns AL=FFh
if DOS 4.01 SHARE was automatically loaded, file sharing is in an
inactive state (due to the undocumented /NC flag used by the autoload
code) until this call is made
DOS 5.0 chains to the previous handler if AL <> 00h on entry
SeeAlso: AX=1080h,INT 21/AH=52h
----------2F1040-----------------------------
INT 2F U - DOS 4 only SHARE internal - ???
AX = 1040h
???
Return: AL = FFh???
SeeAlso: AX=1000h
----------2F1080-----------------------------
INT 2F U - DOS 4 only SHARE internal - TURN ON FILE SHARING CHECKS
AX = 1080h
Return: AL = status
F0h successful
FFh checking was already on
Note: DOS 4.x SHARE has dual functions: FCB support for large (>32M) media
and file sharing checks. The undocumented commandline flag /NC can
be used to disable the sharing code.
SeeAlso: AX=1000h,AX=1081h
----------2F1081-----------------------------
INT 2F U - DOS 4 only SHARE internal - TURN OFF FILE SHARING CHECKS
AX = 1081h
Return: AL = status
F0h successful
FFh checking was already off
Note: (see AX=1080h)
SeeAlso: AX=1000h,AX=1080h
----------2F10FF-----------------------------
INT 2F U - Multiplex - DR-DOS 5.0 - ???
AX = 10FFh
ES:BX -> ???
Note: sets pointer in kernel
----------2F1100-----------------------------
INT 2F - NETWORK REDIRECTOR - INSTALLATION CHECK
AX = 1100h
Return: AL = 00h not installed, OK to install
01h not installed, not OK to install
FFh installed
Notes: called by DOS 3.1+ kernel
In DOS 4.x only, the 11xx calls are all in IFSFUNC.EXE, not in the
PC LAN Program redirector; DOS 5.0 moves the calls back into the
redirector
----------2F1100-----------------------------
INT 2F - MSCDEX (MS CD-ROM Extensions) - INSTALLATION CHECK
AX = 1100h
STACK: WORD DADAh
Return: AL = 00h not installed, OK to install
STACK unchanged
= 01h not installed, not OK to install
STACK unchanged
= FFh installed
STACK: WORD ADADh
----------2F1101-----------------------------
INT 2F U - NETWORK REDIRECTOR - REMOVE REMOTE DIRECTORY
AX = 1101h
SS = DOS DS
SDA first filename pointer -> fully-qualified directory name
SDA CDS pointer -> current directory structure for drive with dir
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
Note: called by DOS 3.1+ kernel
SeeAlso: AX=1103h,AX=1105h,INT 21/AH=3Ah,INT 21/AH=60h
----------2F1102-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - REMOVE REMOTE DIRECTORY
AX = 1102h
SS = DOS DS
SDA first filename pointer -> fully-qualified directory name
SDA CDS pointer -> current directory structure for drive with dir
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
Note: appears to be identical to AX=1101h
SeeAlso: AX=1101h
----------2F1103-----------------------------
INT 2F U - NETWORK REDIRECTOR - MAKE REMOTE DIRECTORY
AX = 1103h
SS = DOS DS
SDA first filename pointer -> fully-qualified directory name
SDA CDS pointer -> current directory structure for drive with dir
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
Note: called by DOS 3.1+ kernel
SeeAlso: AX=1101h,AX=1105h,INT 21/AH=39h,INT 21/AH=60h
----------2F1104-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - MAKE REMOTE DIRECTORY
AX = 1104h
SS = DOS DS
SDA first filename pointer -> fully-qualified directory name
SDA CDS pointer -> current directory structure for drive with dir
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
Note: appears to be identical to AX=1103h
SeeAlso: AX=1103h
----------2F1105-----------------------------
INT 2F U - NETWORK REDIRECTOR - CHDIR
AX = 1105h
SS = DOS DS
SDA first filename pointer -> fully-qualified directory name
SDA CDS pointer -> current directory structure for drive with dir
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
CDS updated with new path
Notes: called by DOS 3.1+ kernel
directory string in CDS should not have a terminating backslash unless
the current directory is the root
SeeAlso: AX=1101h,AX=1103h,INT 21/AH=3Bh,INT 21/AH=60h
----------2F1106-----------------------------
INT 2F U - NETWORK REDIRECTOR - CLOSE REMOTE FILE
AX = 1106h
ES:DI -> SFT
SFT DPB field -> DPB of drive containing file
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
SFT updated (redirector must decrement open count, which may be
done with INT 2F/AX=1208h)
Note: called by DOS 3.1+ kernel
SeeAlso: AX=1201h,AX=1208h,AX=1227h,INT 21/AH=3Eh
----------2F1107-----------------------------
INT 2F U - NETWORK REDIRECTOR - COMMIT REMOTE FILE
AX = 1107h
ES:DI -> SFT
SFT DPB field -> DPB of drive containing file
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
all buffers for file flushed
directory entry updated
Note: called by DOS 3.1+ kernel
SeeAlso: INT 21/AH=68h,INT 21/AX=5D01h
----------2F1108-----------------------------
INT 2F U - NETWORK REDIRECTOR - READ FROM REMOTE FILE
AX = 1108h
ES:DI -> SFT
SFT DPB field -> DPB of drive containing file
CX = number of bytes
SS = DOS DS
SDA DTA field -> user buffer
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
CX = number of bytes read (0000h = end of file)
SFT updated
Note: called by DOS 3.1+ kernel
SeeAlso: AX=1109h,AX=1229h,INT 21/AH=3Fh,INT 21/AX=5D06h
----------2F1109-----------------------------
INT 2F U - NETWORK REDIRECTOR - WRITE TO REMOTE FILE
AX = 1109h
ES:DI -> SFT
SFT DPB field -> DPB of drive containing file
CX = number of bytes
SS = DOS DS
SDA DTA field -> user buffer
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
CX = number of bytes written
SFT updated
Note: called by DOS 3.1+ kernel
SeeAlso: AX=1107h,AX=1108h,INT 21/AH=40h,INT 21/AX=5D06h
----------2F110A-----------------------------
INT 2F U - NETWORK REDIRECTOR (DOS 3.x only) - LOCK REGION OF FILE
AX = 110Ah
BX = file handle
CX:DX = starting offset
SI = high word of size
STACK: WORD low word of size
ES:DI -> SFT
SFT DPB field -> DPB of drive containing file
SS = DOS DS
Return: CF set on error
AL = DOS error code (see INT 21/AH=59h)
STACK unchanged
Notes: called by DOS 3.10-3.31 kernel
the redirector is expected to resolve lock conflicts
SeeAlso: AX=110Bh,INT 21/AH=5Ch
----------2F110A-----------------------------
INT 2F U - NETWORK REDIRECTOR (DOS 4+) - LOCK/UNLOCK REGION OF FILE
AX = 110Ah
BL = function
00h lock
01h unlock
DS:DX -> parameter block (see below)
ES:DI -> SFT
SFT DPB field -> DPB of drive containing file
SS = DOS DS
Return: CF set on error
AL = DOS error code (see INT 21/AH=59h)
Notes: called by DOS 4.0+ kernel
the redirector is expected to resolve lock conflicts
SeeAlso: AX=110Bh,INT 21/AH=5Ch

Format of parameter block:
Offset Size Description
00h DWORD start offset
04h DWORD size of region
----------2F110B-----------------------------
INT 2F U - NETWORK REDIRECTOR (DOS 3.x only) - UNLOCK REGION OF FILE
AX = 110Bh
BX = file handle
CX:DX = starting offset
SI = high word of size
STACK: WORD low word of size
ES:DI -> SFT for file
SFT DPB field -> DPB of drive containing file
Return: CF set on error
AL = DOS error code (see INT 21/AH=59h)
STACK unchanged
Note: called by DOS 3.1-3.31 kernel; DOS 4.0+ calls AX=110Ah instead
SeeAlso: AX=110Ah,INT 21/AH=5Ch
----------2F110C-----------------------------
INT 2F U - NETWORK REDIRECTOR - GET DISK SPACE
AX = 110Ch
ES:DI -> current directory structure for desired drive
Return: AL = sectors per cluster
AH = media ID byte
BX = total clusters
CX = bytes per sector
DX = number of available clusters
Note: called by DOS 3.1+ kernel
SeeAlso: INT 21/AH=36h
----------2F110D-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - ???
AX = 110Dh
SDA first filename pointer -> name of file
???
Return: ???
Note: appears to be similar to AX=110Fh
SeeAlso: AX=110Fh
----------2F110E-----------------------------
INT 2F U - NETWORK REDIRECTOR - SET REMOTE FILE'S ATTRIBUTES
AX = 110Eh
SS = DOS DS
SDA first filename pointer -> fully-qualified name of file
SDA CDS pointer -> current directory structure for drive with file
STACK: WORD new file attributes
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
STACK unchanged
Note: called by DOS 3.1+ kernel
SeeAlso: AX=110Fh,INT 21/AX=4301h,INT 21/AH=60h
----------2F110F-----------------------------
INT 2F U - NETWORK REDIRECTOR - GET REMOTE FILE'S ATTRIBUTES AND SIZE
AX = 110Fh
SS = DOS DS
SDA first filename pointer -> fully-qualified name of file
SDA CDS pointer -> current directory structure for drive with file
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
AX = file attributes
BX:DI = file size
Note: called by DOS 3.1+ kernel
SeeAlso: AX=110Eh,INT 21/AX=4300h,INT 21/AH=60h
----------2F1110-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - ???
AX = 1110h
SDA first filename pointer -> name of file
???
Return: ???
Note: appears to be similar to AX=110Eh
SeeAlso: AX=110Eh
----------2F1111-----------------------------
INT 2F U - NETWORK REDIRECTOR - RENAME REMOTE FILE
AX = 1111h
SS = DS = DOS DS
SDA first filename pointer = offset of fully-qualified old name
SDA second filename pointer = offset of fully-qualified new name
SDA CDS pointer -> current directory structure for drive with file
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
Note: called by DOS 3.1+ kernel
SeeAlso: INT 21/AH=56h,INT 21/AH=60h
----------2F1112-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - ???
AX = 1112h
SS = DS = DOS DS
SDA first filename pointer -> name of file
???
Return: ???
SeeAlso: AX=1111h
----------2F1113-----------------------------
INT 2F U - NETWORK REDIRECTOR - DELETE REMOTE FILE
AX = 1113h
SS = DS = DOS DS
SDA first filename pointer -> fully-qualified filename in DOS DS
SDA CDS pointer -> current directory structure for drive with file
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
Notes: called by DOS 3.1+ kernel
the filespec may contain wildcards
SeeAlso: INT 21/AH=41h,INT 21/AH=60h
----------2F1114-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - ???
AX = 1114h
SDA first filename pointer -> name of file
???
Return: ???
SeeAlso: AX=1113h
----------2F1115-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - ???
AX = 1115h
SS = DOS DS
ES:DI -> SFT ???
???
Return: ???
SeeAlso: AX=112Eh
----------2F1116-----------------------------
INT 2F U - NETWORK REDIRECTOR - OPEN EXISTING REMOTE FILE
AX = 1116h
ES:DI -> uninitialized SFT
SS = DOS DS
SDA first filename pointer -> fully-qualified name of file to open
STACK: WORD file open mode (see INT 21/AH=3Dh)
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
SFT filled (except handle count, which DOS manages itself)
STACK unchanged
Note: called by DOS 3.1+ kernel
SeeAlso: AX=1106h,AX=1117h,AX=1118h,AX=112Eh,INT 21/AH=3Dh,INT 21/AH=60h
----------2F1117-----------------------------
INT 2F U - NETWORK REDIRECTOR - CREATE/TRUNCATE REMOTE FILE
AX = 1117h
ES:DI -> uninitialized SFT
SS = DOS DS
SDA first filename pointer -> fully-qualified name of file to open
SDA CDS pointer -> current directory structure for drive with file
STACK: WORD file creation mode
low byte = file attributes
high byte = 00h normal create, 01h create new file
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
SFT filled (except handle count, which DOS manages itself)
STACK unchanged
Note: called by DOS 3.1+ kernel
SeeAlso: AX=1106h,AX=1116h,AX=1118h,AX=112Eh,INT 21/AH=3Ch,INT 21/AH=60h
----------2F1118-----------------------------
INT 2F U - NETWORK REDIRECTOR - CREATE/TRUNCATE FILE WITHOUT CDS
AX = 1118h
ES:DI -> uninitialized SFT
SS = DOS DS
SDA first filename pointer -> fully-qualified name of file
STACK: WORD file creation mode
low byte = file attributes
high byte = 00h normal create, 01h create new file
Return: ???
STACK unchanged
Note: called by DOS 3.1+ kernel when creating a file on a drive for which the
SDA CDS pointer has offset FFFFh
SeeAlso: AX=1106h,AX=1116h,AX=1117h,AX=112Eh,INT 21/AH=60h
----------2F1119-----------------------------
INT 2F U - NETWORK REDIRECTOR - FIND FIRST FILE WITHOUT CDS
AX = 1119h
SS = DS = DOS DS
[DTA] = uninitialized 21-byte findfirst search data (see INT 21/AH=4Eh)
SDA first filename pointer -> fully-qualified search template
SDA search attribute = attribute mask for search
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
[DTA] = updated findfirst search data
(bit 7 of first byte must be set)
[DTA+15h] = standard directory entry for file
Notes: called by DOS 3.1+ kernel
DOS 4.x IFSFUNC returns CF set, AX=0003h
----------2F111A-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - ???
AX = 111Ah
???
Return: CF set
AX = error code (03h for DOS 4.01 IFSFUNC)
----------2F111B-----------------------------
INT 2F U - NETWORK REDIRECTOR - FINDFIRST
AX = 111Bh
SS = DS = DOS DS
[DTA] = uninitialized 21-byte findfirst search data (see INT 21/AH=4Eh)
SDA first filename pointer -> fully-qualified search template
SDA CDS pointer -> current directory structure for drive with file
SDA search attribute = attribute mask for search
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
[DTA] = updated findfirst search data
(bit 7 of first byte must be set)
[DTA+15h] = standard directory entry for file
Note: called by DOS 3.1+ kernel
SeeAlso: AX=111Ch,INT 21/AH=4Eh,INT 21/AH=60h
----------2F111C-----------------------------
INT 2F U - NETWORK REDIRECTOR - FINDNEXT
AX = 111Ch
SS = DS = DOS DS
[DTA] = 21-byte findfirst search data (see INT 21/AH=4Eh)
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
[DTA] = updated findfirst search data
(bit 7 of first byte must be set)
[DTA+15h] = standard directory entry for file
Note: called by DOS 3.1+ kernel
SeeAlso: AX=111Bh,INT 21/AH=4Fh
----------2F111D-----------------------------
INT 2F U - NETWORK REDIRECTOR - CLOSE ALL REMOTE FILES FOR PROCESS
AX = 111Dh
DS???
SS = DOS DS
Return: ???
Notes: called by DOS 3.1+ kernel
closes all FCBs opened by process
SeeAlso: INT 21/AX=5D04h
----------2F111E-----------------------------
INT 2F U - NETWORK REDIRECTOR - DO REDIRECTION
AX = 111Eh
SS = DOS DS
STACK: WORD function to execute
5F00h get redirection mode
BL = type (03h printer, 04h disk)
Return: BH = state (00h off, 01h on)
5F01h set redirection mode
BL = type (03h printer, 04h disk)
BH = state (00h off, 01h on)
5F02h get redirection list entry
BX = redirection list index
DS:SI -> 16-byte local device name buffer
ES:DI -> 128-byte network name buffer
Return: must set user's BX to device type and CX to
stored parameter value, using AX=1218h to get
stack frame address
5F03h redirect device
BL = device type (see INT 21/AX=5F03h)
CX = stored parameter value
DS:SI -> ASCIZ source device name
ES:DI -> destination ASCIZ network path + ASCIZ passwd
5F04h cancel redirection
DS:SI -> ASCIZ device name or network path
5F05h get redirection list extended entry
BX = redirection list index
DS:SI -> buffer for ASCIZ source device name
ES:DI -> buffer for destination ASCIZ network path
Return: BH = status flag
BL = type (03h printer, 04h disk)
CX = stored parameter value
BP = NETBIOS local session number
5F06h similar to 5F05h???
Return: CF set on error
AX = error code (see INT 21/AH=59h)
STACK unchanged
Note: called by DOS 3.1+ kernel
SeeAlso: INT 21/AX=5F00h,INT 21/AX=5F01h,INT 21/AX=5F02h,INT 21/AX=5F03h
SeeAlso: INT 21/AX=5F04h,INT 21/AX=5F05h,INT 21/AX=5F06h
----------2F111F-----------------------------
INT 2F U - NETWORK REDIRECTOR - PRINTER SETUP
AX = 111Fh
STACK: WORD function
5E02h set printer setup
5E03h get printer setup
5E04h set printer mode
5E05h get printer mode
Return: CF set on error
AX = error code (see INT 21/AH=59h)
STACK unchanged
Note: called by DOS 3.1+ kernel
SeeAlso: INT 21/AX=5E02h,INT 21/AX=5E03h,INT 21/AX=5E04h,INT 21/AX=5E05h
----------2F1120-----------------------------
INT 2F U - NETWORK REDIRECTOR - FLUSH ALL DISK BUFFERS
AX = 1120h
DS = DOS DS
???
Return: CF clear (successful)
Notes: called by DOS 3.1+ kernel
uses CDS array pointer and LASTDRIVE= entries in DOS list of lists
SeeAlso: INT 21/AH=0Dh,INT 21/AX=5D01h
----------2F1121-----------------------------
INT 2F U - NETWORK REDIRECTOR - SEEK FROM END OF REMOTE FILE
AX = 1121h
CX:DX = offset (in bytes) from end
ES:DI -> SFT
SFT DPB field -> DPB of drive with file
SS = DOS DS
Return: CF set on error
AL = DOS error code (see INT 21/AH=59h)
CF clear if successful
DX:AX = new file position
Note: called by DOS 3.1+ kernel
SeeAlso: AX=1228h,INT 21/AH=42h
----------2F1122-----------------------------
INT 2F U - NETWORK REDIRECTOR - PROCESS TERMINATION HOOK
AX = 1122h
SS = DOS DS
???
Return: ???
Note: called by DOS 3.1+ kernel
----------2F1123-----------------------------
INT 2F U - NETWORK REDIRECTOR - QUALIFY REMOTE FILENAME
AX = 1123h
DS:SI -> ASCIZ filename to canonicalize
ES:DI -> 128-byte buffer for qualified name
Return: CF set if not resolved
Notes: called by MSDOS 3.1+ kernel, but not called by DR-DOS 5.0 unless the
filename matches the name of a character device
called first when DOS attempts to resolve a filename (unless inside an
AX=5D00h server call); if this fails, DOS resolves the name locally
SeeAlso: AX=1221h,INT 21/AH=60h
----------2F1124-----------------------------
INT 2F U - NETWORK REDIRECTOR - PRINTER OFF???
AX = 1124h
ES:DI -> SFT
SS = DOS DS
???
Return: CX = ???
Note: called by DOS 3.1+ kernel if AX=1126h returns CF set
SeeAlso: AX=1126h
----------2F1125-----------------------------
INT 2F U - NETWORK REDIRECTOR - REDIRECTED PRINTER MODE
AX = 1125h
STACK: WORD subfunction
5D07h get print stream state
Return: DL = current state
5D08h set print stream state
DL = new state
5D09h finish print job
Return: CF set on error
AX = error code (see INT 21/AH=59h)
STACK unchanged
Note: called by DOS 3.1+ kernel
SeeAlso: INT 21/AX=5D07h,INT 21/AX=5D08h,INT 21/AX=5D09h
----------2F1126-----------------------------
INT 2F U - NETWORK REDIRECTOR - PRINTER ON/OFF???
AX = 1126h
ES:DI -> SFT for file handle 4???
SS = DOS DS???
???
Return: CF set on error
Notes: called by DOS 3.1+ kernel
called when print echoing (^P, ^PrtSc) changes state and STDPRN has
bit 11 of the device information word in the SFT set
SeeAlso: AX=1124h
----------2F1127-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - UNUSED
AX = 1127h
Return: CF set
AX = 0001h (invalid function) (see INT 21/AH=59h)
----------2F1128-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - UNUSED
AX = 1128h
Return: CF set
AX = 0001h (invalid function) (see INT 21/AH=59h)
----------2F1129-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - UNUSED
AX = 1129h
Return: CF set
AX = 0001h (invalid function) (see INT 21/AH=59h)
----------2F112A-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - ???
AX = 112Ah
DS = DOS DS
???
Return: ???
Note: does something to each IFS driver
----------2F112B-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - GENERIC IOCTL???
AX = 112Bh
SS = DOS DS
CX = function/category
DS:DX -> parameter block
STACK: WORD value of AX on entry to INT 21 (440Ch or 440Dh)
???
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
Note: called by DOS 4.0 kernel
----------2F112C-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - ???
AX = 112Ch
SS = DOS DS
SDA current SFT pointer -> SFT for file
???
Return: CF set on error
Note: called by SHARE in DOS 5.0
----------2F112D-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - ???
AX = 112Dh
BL = subfunction (value of AL on INT 21)
04h truncate open file to zero length
ES:DI -> SFT for file
Return: CF clear
else ???
Return: CX = ??? (00h or 02h for DOS 4.01)
ES:DI -> SFT
SS = DOS DS
Return: DS = DOS DS
Note: called by DOS 4.0 kernel on INT 21/AX=5702h,INT 21/AX=5703h,
INT 21/AX=5704h
----------2F112E-----------------------------
INT 2F U - NETWORK REDIRECTOR (DOS 4+) - EXTENDED OPEN/CREATE FILE
AX = 112Eh
SS = DS = DOS DS
ES:DI -> uninitialized SFT for file
STACK: WORD file attribute for created/truncated file
low byte = file attributes
high byte = 00h normal create/open, 01h create new file
SDA first filename pointer -> fully-qualified filename
SDA extended file open action = action code (see INT 21/AX=6C00h)
SDA extended file open mode = open mode for file (see INT 21/AX=6C00h)
Return: CF set on error
AX = error code
CF clear if successful
CX = result code
01h file opened
02h file created
03h file replaced (truncated)
SFT initialized (except handle count, which DOS manages itself)
Note: called by DOS 4.0 kernel
SeeAlso: AX=1115h,AX=1116h,AX=1117h,INT 21/AX=6C00h
----------2F112F-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - ???
AX = 112Fh
SS = DOS DS
STACK: WORD function in low byte
00h ???
DS:SI -> Current Directory Structure???
CL = drive (1=A:)
01h ???
DS:SI -> ???
CL = file handle???
02h ???
DS:SI -> Current Directory Structure???
DI = ???
CX = drive (1=A:)
???
Return: CF set on error
AX = DOS error code (see INT 21/AH=59h)
CF clear if successful
Note: called by DOS 4.0 kernel
SeeAlso: INT 21/AH=6Bh
----------2F1130-----------------------------
INT 2F U - IFSFUNC.EXE (DOS 4.x only) - GET IFSFUNC SEGMENT
AX = 1130h
Return: ES = CS of resident IFSFUNC
----------2F1186-----------------------------
INT 2F - LAN Manager Enhanced DOS API - DosReadAsynchNmPipe
AX = 1186h
???
Return: ???
Note: LAN Manager enhance mode adds features beyond the standard redirector
file/printer services
SeeAlso: AX=118Fh,INT 21/AX=5F39h
----------2F118A-----------------------------
INT 2F - LAN Manager 2.0 DOS Enhanced ENCRYPT.EXE - STREAM ENCRYPTION SERVICE
AX = 118Ah
???
Return: ???
SeeAlso: AX=1186h,AH=41h,AH=42h,AH=4Bh
----------2F118F-----------------------------
INT 2F - LAN Manager Enhanced DOS API - DosWriteAsynchNmPipe
AX = 118Fh
???
Return: ???
SeeAlso: AX=1186h,INT 21/AX=5F3Ah
----------2F1200-----------------------------
INT 2F U - DOS 3+ internal - INSTALLATION CHECK
AX = 1200h
Return: AL = FFh (for compatibility with other INT 2F functions)
----------2F1201-----------------------------
INT 2F U - DOS 3+ internal - CLOSE CURRENT FILE
AX = 1201h
SS = DOS DS (must be using a DOS internal stack)
SDA current SFT pointer -> SFT of file to close
Return: CF set on error
BX???
CX new reference count of SFT
ES:DI -> SFT for file
SeeAlso: AX=1106h,AX=1227h,INT 21/AH=3Eh
----------2F1202-----------------------------
INT 2F U - DOS 3+ internal - GET INTERRUPT ADDRESS
AX = 1202h
STACK: WORD vector number
Return: ES:BX -> interrupt vector
STACK unchanged
----------2F1203-----------------------------
INT 2F U - DOS 3+ internal - GET DOS DATA SEGMENT
AX = 1203h
Return: DS = data segment of IBMDOS.COM/MSDOS.SYS
Note: for DOS prior to version 5.0, the data segment is the same as the code
segment
----------2F1204-----------------------------
INT 2F U - DOS 3+ internal - NORMALIZE PATH SEPARATOR
AX = 1204h
STACK: WORD character to normalize
Return: AL = normalized character (forward slash turned to backslash, all
others unchanged)
ZF set if path separator
STACK unchanged
----------2F1205-----------------------------
INT 2F U - DOS 3+ internal - OUTPUT CHARACTER TO STANDARD OUTPUT
AX = 1205h
STACK: WORD character to output
Return: STACK unchanged
Note: can be called only from within DOS
----------2F1206-----------------------------
INT 2F U - DOS 3+ internal - INVOKE CRITICAL ERROR
AX = 1206h
DI = error code
BP:SI -> device driver header
SS = DOS DS (must be using a DOS internal stack)
STACK: WORD value to be passed to INT 24 in AX
Return: AL = 0-3 for Abort, Retry, Ignore, Fail
STACK unchanged
SeeAlso: INT 24
----------2F1207-----------------------------
INT 2F U - DOS 3+ internal - MAKE DISK BUFFER MOST-RECENTLY USED
AX = 1207h
DS:DI -> disk buffer
Return: nothing
Desc: move the indicated buffer to the end of the disk buffer chain (least-
recently used is first); under DOS 3.3, the buffer is then moved to
the start of the disk buffer chain if it was marked unused
Note: can be called only from within DOS
SeeAlso: AX=120Fh
----------2F1208-----------------------------
INT 2F U - DOS 3+ internal - DECREMENT SFT REFERENCE COUNT
AX = 1208h
ES:DI -> SFT
Return: AX = original value of reference count
Notes: if the reference count was 1, it is set to FFFFh (since 0 indicates
that the SFT is not in use). It is the caller's responsibility to
set the reference count to zero after cleaning up.
used by network redirectors such as MSCDEX
SeeAlso: AX=1106h
----------2F1209-----------------------------
INT 2F U - DOS 3+ internal - FLUSH AND FREE DISK BUFFER
AX = 1209h
DS:DI -> disk buffer
Return: disk buffer marked unused, contents written to disk if buffer dirty
Note: can be called only from within DOS
SeeAlso: AX=120Eh,AX=1215h
----------2F120A-----------------------------
INT 2F U - DOS 3+ internal - PERFORM CRITICAL ERROR INTERRUPT
AX = 120Ah
DS = SS = DOS DS (must be using a DOS internal stack)
STACK: WORD extended error code
Return: AL = user response (0=ignore, 1=retry, 2=abort, 3=fail)
CF clear if retry, set otherwise
STACK unchanged
Notes: can only be called during a DOS function call, as it uses various
fields in the SDA to set up the registers for the INT 24
reportedly sets current DPB's first root directory sector to 1
SeeAlso: INT 24
----------2F120B-----------------------------
INT 2F U - DOS 3+ internal - SIGNAL SHARING VIOLATION TO USER
AX = 120Bh
ES:DI -> system file table entry for previous open of file
STACK: WORD extended error code (should be 20h--sharing violation)
Return: CF clear if operation should be retried
CF set if operation should not be retried
AX = error code (20h) (see INT 21/AH=59h)
STACK unchanged
Notes: can only be called during a DOS function call
should only be called if an attempt was made to open an already-open
file contrary to the sharing rules
invokes INT 24 if SFT file opened via FCB or in compatibility mode with
inheritance allowed
----------2F120C-----------------------------
INT 2F U - DOS 3+ internal - OPEN DEVICE AND SET SFT OWNER???
AX = 120Ch
SDA current SFT pointer -> SFT for file
DS = DOS DS
SS = DOS DS (must be using a DOS internal stack)
Return: ES, DI, AX destroyed
Notes: invokes "device open" call on device driver for SFT
changes owner of last-accessed SFT to calling process if it was opened
via FCB
called by network redirectors such as MSCDEX
----------2F120D-----------------------------
INT 2F U - DOS 3+ internal - GET DATE AND TIME
AX = 120Dh
SS = DOS DS (must be using a DOS internal stack)
Return: AX = current date in packed format (see INT 21/AX=5700h)
DX = current time in packed format (see INT 21/AX=5700h)
SeeAlso: INT 21/AH=2Ah,INT 21/AH=2Ch
----------2F120E-----------------------------
INT 2F U - DOS 3+ internal - MARK ALL DISK BUFFERS UNREFERENCED
AX = 120Eh
SS = DOS DS (must be using a DOS internal stack)
Return: DS:DI -> first disk buffer
Note: clears "referenced" flag on all disk buffers
SeeAlso: AX=1209h,AX=1210h,INT 21/AH=0Dh
----------2F120F-----------------------------
INT 2F U - DOS 3+ internal - MAKE BUFFER MOST RECENTLY USED
AX = 120Fh
DS:DI -> disk buffer
SS = DOS DS (must be using a DOS internal stack)
Return: DS:DI -> next buffer in buffer list
Desc: move the indicated buffer to the end of the disk buffer chain (least-
recently used is first); under DOS 3.3, the buffer is then moved to
the start of the disk buffer chain if it was marked unused
Note: this function is the same as AX=1207h except that it returns a
pointer to the buffer following the specified buffer in the buffer
chain
SeeAlso: AX=1207h
----------2F1210-----------------------------
INT 2F U - DOS 3+ internal - FIND UNREFERENCED DISK BUFFER
AX = 1210h
DS:DI -> first disk buffer to check
Return: ZF clear if found
DS:DI -> first unreferenced disk buffer
ZF set if not found
SeeAlso: AX=120Eh
----------2F1211-----------------------------
INT 2F U - DOS 3+ internal - NORMALIZE ASCIZ FILENAME
AX = 1211h
DS:SI -> ASCIZ filename to normalize
ES:DI -> buffer for normalized filename
Return: destination buffer filled with uppercase filename, with slashes turned
to backslashes
SeeAlso: AX=121Eh,AX=1221h
----------2F1212-----------------------------
INT 2F U - DOS 3+ internal - GET LENGTH OF ASCIZ STRING
AX = 1212h
ES:DI -> ASCIZ string
Return: CX = length of string
SeeAlso: AX=1225h
----------2F1213-----------------------------
INT 2F U - DOS 3+ internal - UPPERCASE CHARACTER
AX = 1213h
STACK: WORD character to convert to uppercase
Return: AL = uppercase character
STACK unchanged
----------2F1214-----------------------------
INT 2F U - DOS 3+ internal - COMPARE FAR POINTERS
AX = 1214h
DS:SI = first pointer
ES:DI = second pointer
Return: ZF set if pointers are equal, ZF clear if not equal
----------2F1215-----------------------------
INT 2F U - DOS 3+ internal - FLUSH BUFFER
AX = 1215h
DS:DI -> disk buffer
SS = DOS DS (must be using a DOS internal stack)
STACK: WORD drives for which to skip buffer
ignore buffer if drive same as high byte, or bytes differ and
the buffer is for a drive OTHER than that given in low byte
Return: STACK unchanged
Note: can be called only from within DOS
SeeAlso: AX=1209h
----------2F1216-----------------------------
INT 2F U - DOS 3+ internal - GET ADDRESS OF SYSTEM FILE TABLE
AX = 1216h
BX = system file table entry number
Return: CF clear if successful
ES:DI -> system file table entry
CF set if BX greater than FILES=
SeeAlso: AX=1220h
----------2F1217-----------------------------
INT 2F U - DOS 3+ internal - GET CURRENT DIRECTORY STRUCTURE FOR DRIVE
AX = 1217h
SS = DOS DS (must be using a DOS internal stack)
STACK: WORD drive (0 = A:, 1 = B:, etc)
Return: CF set on error
(drive > LASTDRIVE)
CF clear if successful
DS:SI -> current directory structure for specified drive
STACK unchanged
SeeAlso: AX=1219h
----------2F1218-----------------------------
INT 2F U - DOS 3+ internal - GET CALLER'S REGISTERS
AX = 1218h
Return: DS:SI -> saved caller's AX,BX,CX,DX,SI,DI,BP,DS,ES (on stack)
Note: only valid while within DOS
----------2F1219-----------------------------
INT 2F U - DOS 3+ internal - SET DRIVE???
AX = 1219h
SS = DOS DS (must be using a DOS internal stack)
STACK: WORD drive (0 = default, 1 = A:, etc)
Return: ???
STACK unchanged
Notes: calls AX=1217h
builds a current directory structure if inside server call
(INT 21/AX=5D00h)
SeeAlso: AX=1217h,AX=121Fh
----------2F121A-----------------------------
INT 2F U - DOS 3+ internal - GET FILE'S DRIVE
AX = 121Ah
DS:SI -> filename
Return: AL = drive (0 = default, 1 = A:, etc, FFh = invalid)
DS:SI -> filename without leading X: (if present)
SeeAlso: INT 21/AH=19h,INT 21/AH=60h
----------2F121B-----------------------------
INT 2F U - DOS 3+ internal - SET YEAR/LENGTH OF FEBRUARY
AX = 121Bh
CL = year - 1980
Return: AL = number of days in February
Note: requires DS to be set to the DOS code segment
SeeAlso: INT 21/AH=2Bh
----------2F121C-----------------------------
INT 2F U - DOS 3+ internal - CHECKSUM MEMORY
AX = 121Ch
DS:SI -> start of memory to checksum
CX = number of bytes
DX = initial checksum
SS = DOS DS (must be using a DOS internal stack)
Return: AX, CX destroyed
DX = checksum
DS:SI -> first byte after checksummed range
Note: used by DOS to determine day count since 1/1/80 given a date
SeeAlso: AX=121Dh
----------2F121D-----------------------------
INT 2F U - DOS 3+ internal - SUM MEMORY
AX = 121Dh
DS:SI -> memory to add up
CX = 0000h
DX = limit
Return: AL = byte which exceeded limit
CX = number of bytes before limit exceeded
DX = remainder after adding first CX bytes
DS:SI -> byte beyond the one which exceeded the limit
Note: used by DOS to determine year or month given day count since 1/1/80
SeeAlso: AX=121Ch
----------2F121E-----------------------------
INT 2F U - DOS 3+ internal - COMPARE FILENAMES
AX = 121Eh
DS:SI -> first ASCIZ filename
ES:DI -> second ASCIZ filename
Return: ZF set if filenames equivalent, ZF clear if not
SeeAlso: AX=1211h,AX=1221h
----------2F121F-----------------------------
INT 2F U - DOS 3+ internal - BUILD CURRENT DIRECTORY STRUCTURE
AX = 121Fh
SS = DOS DS (must be using a DOS internal stack)
STACK: WORD drive letter
Return: ES:DI -> current directory structure (will be overwritten by next call)
STACK unchanged
----------2F1220-----------------------------
INT 2F U - DOS 3+ internal - GET JOB FILE TABLE ENTRY
AX = 1220h
BX = file handle
Return: CF set on error
AL = 6 (invalid file handle)
CF clear if successful
ES:DI -> JFT entry for file handle in current process
Note: the byte pointed at by ES:DI contains the number of the SFT for the
file handle, or FFh if the handle is not open
SeeAlso: AX=1216h,AX=1229h
----------2F1221-----------------------------
INT 2F U - DOS 3+ internal - CANONICALIZE FILE NAME
AX = 1221h
DS:SI -> file name to be fully qualified
ES:DI -> 128-byte buffer for resulting canonical file name
SS = DOS DS (must be using a DOS internal stack)
Return: (see INT 21/AH=60h)
Note: identical to INT 21/AH=60h
SeeAlso: AX=1123h,INT 21/AH=60h
----------2F1222-----------------------------
INT 2F U - DOS 3+ internal - SET EXTENDED ERROR INFO
AX = 1222h
SS = DOS data segment
SS:SI -> 4-byte records
BYTE error code, FFh = last record
BYTE error class, FFh = don't change
BYTE suggested action, FFh = don't change
BYTE error locus, FFh = don't change
SDA error code set
Return: SI destroyed
SDA error class, error locus, and suggested action fields set
Note: can be called only from within DOS
SeeAlso: AX=122Dh,INT 21/AH=59h
----------2F1223-----------------------------
INT 2F U - DOS 3+ internal - CHECK IF CHARACTER DEVICE
AX = 1223h
DS = DOS DS
SS = DOS DS (must be using a DOS internal stack)
SDA+218h (DOS 3.10-3.30) = eight-character blank-padded name
SDA+22Bh (DOS 4.0-5.0) = eight-character blank-padded name
Return: CF set if no character device by that name found
CF clear if found
BH = low byte of device attribute word
Note: can only be called from within DOS
SeeAlso: INT 21/AX=5D06h,INT 21/AX=5D0Bh
----------2F1224-----------------------------
INT 2F U - DOS 3+ internal - DELAY
AX = 1224h
SS = DOS DS (must be using a DOS internal stack)
Return: after delay set by INT 21/AX=440Bh, unless in server call
(INT 21/AX=5D00h)
Note: delay is dependent on the processor speed, and is skipped entirely if
inside a server call
SeeAlso: INT 21/AX=440Bh,INT 21/AH=52h
----------2F1225-----------------------------
INT 2F U - DOS 3+ internal - GET LENGTH OF ASCIZ STRING
AX = 1225h
DS:SI -> ASCIZ string
Return: CX = length of string
SeeAlso: AX=1212h
----------2F1226-----------------------------
INT 2F U - DOS 3.3+ internal - OPEN FILE
AX = 1226h
CL = access mode
DS:DX -> ASCIZ filename
SS = DOS DS (must be using a DOS internal stack)
Return: CF set on error
AL = error code (see INT 21/AH=59h)
CF clear if successful
AX = file handle
Notes: can only be called from within DOS
equivalent to INT 21/AH=3Dh
SeeAlso: AX=1227h,INT 21/AH=3Dh
----------2F1227-----------------------------
INT 2F U - DOS 3.3+ internal - CLOSE FILE
AX = 1227h
BX = file handle
SS = DOS DS (must be using a DOS internal stack)
Return: CF set on error
AL = 06h invalid file handle
CF clear if successful
Notes: can only be called from within DOS
equivalent to INT 21/AH=3Eh
SeeAlso: AX=1106h,AX=1201h,AX=1226h,INT 21/AH=3Eh
----------2F1228BP4200-----------------------
INT 2F U - DOS 3.3+ internal - MOVE FILE POINTER
AX = 1228h
BP = 4200h, 4201h, 4202h (see INT 21/AH=42h)
BX = file handle
CX:DX = offset in bytes
SS = DOS DS (must be using a DOS internal stack)
Return: as for INT 21/AH=42h
Notes: equivalent to INT 21/AH=42h, but may only be called from inside a DOS
function call
sets user stack frame pointer to dummy buffer, moves BP to AX, performs
LSEEK, and restores frame pointer
SeeAlso: INT 21/AH=42h
----------2F1229-----------------------------
INT 2F U - DOS 3.3+ internal - READ FROM FILE
AX = 1229h
BX = file handle
CX = number of bytes to read
DS:DX -> buffer
SS = DOS DS (must be using a DOS internal stack)
Return: as for INT 21/AH=3Fh
Note: equivalent to INT 21/AH=3Fh, but may only be called when already inside
a DOS function call
SeeAlso: AX=1226h,INT 21/AH=3Fh
----------2F122A-----------------------------
INT 2F U - DOS 3.3+ internal - SET FASTOPEN ENTRY POINT
AX = 122Ah
BX = entry point to set (0001h or 0002h)
DS:SI -> FASTOPEN entry point
(entry point not set if SI = FFFFh for DOS 4+)
Return: CF set if specified entry point already set
Notes: entry point in BX is ignored under DOS 3.30
both entry points set to same handler by DOS 4.01

DOS 3.30+ FASTOPEN is called with:
AL = 01h ???
CX = ??? seems to be offset
DI = ??? seems to be offset
SI = offset in DOS DS of filename
AL = 02h ???
AL = 03h open file???
SI = offset in DOS DS of filename
AL = 04h ???
AH = subfunction (00h,01h,02h)
ES:DI -> ???
CX = ??? (subfunctions 01h and 02h only)
Returns: CF set on error or not installed
Note: function 03h calls function 01h first

PCDOS 4.01 FASTOPEN is additionally called with:
AL = 04h ???
AH = 03h
???
AL = 05h ???
AL = 0Bh ???
AL = 0Ch ???
AL = 0Dh ???
AL = 0Eh ???
AL = 0Fh ???
AL = 10h ???

MSDOS 5.0 FASTOPEN is additionally called with:
AL = 04h ???
AH = 03h
???
AL = 05h ???
DL = drive (00h = A:)
???
AL = 06h ???
----------2F122B-----------------------------
INT 2F U - DOS 3.3+ internal - IOCTL
AX = 122Bh
BP = 44xxh
SS = DOS DS (must be using a DOS internal stack)
additional registers as appropriate for INT 21/AX=44xxh
Return: as for INT 21/AH=44h
Notes: equivalent to INT 21/AH=44h, but may only be called when already inside
a DOS function call
sets user stack frame pointer to dummy buffer, moves BP to AX, performs
IOCTL, and restores frame pointer
SeeAlso: INT 21/AH=44h
----------2F122C-----------------------------
INT 2F U - DOS 3.3+ internal - GET DEVICE CHAIN
AX = 122Ch
Return: BX:AX -> header of second device driver (NUL is first) in driver chain
SeeAlso: INT 21/AH=52h
----------2F122D-----------------------------
INT 2F U - DOS 3.3+ internal - GET EXTENDED ERROR CODE
AX = 122Dh
Return: AX = current extended error code
SeeAlso: AX=1222h,INT 21/AH=59h
----------2F122E-----------------------------
INT 2F U - DOS 4+ internal - GET OR SET ERROR TABLE ADDRESSES
AX = 122Eh
DL = subfunction
00h get standard DOS error table
Return: ES:DI -> error table
(DOS 4: errors 00h-12h,50h-5Bh)
(DOS 5: errors 00h-26h,4Fh,51h-59h)
01h set standard DOS error table
ES:DI -> error table
02h get parameter error table (errors 00h-0Ah)
Return: ES:DI -> error table
03h set parameter error table
ES:DI -> error table
04h get critical/SHARE error table (errors 13h-2Bh)
Return: ES:DI -> error table
05h set critical/SHARE error table
ES:DI -> error table
06h get ??? error table
Return: ES:DI -> error table or 0000h:0000h
07h set ??? error table
ES:DI -> error table
08h get error message retriever (see below)
Return: ES:DI -> FAR procedure to fetch error message
09h set ??? error table
ES:DI -> error table
Notes: if the returned segment on a "get" is 0001h, then the offset specifies
the offset of the error message table within COMMAND.COM, and the
procedure returned by DL=08h should be called
DOS 5.0 COMMAND.COM does not allow setting any of the addresses (calls
with DL odd are ignored); they are always returned with segment 0001h
for DOS 5.0, the standard and critical/SHARE error tables are combined
into a single error table
SeeAlso: AX=0500h,INT 21/AH=59h

Format of DOS 4.x error table:
Offset Size Description
00h BYTE FFh
01h 2 BYTEs 04h,00h (DOS version???)
03h BYTE number of error headers following
04h 2N WORDs table of all error headers for table
Offset Size Description
00h WORD error message number
02h WORD offset of error message from start of header
error messages are count byte followed by msg
Note: DOS 5 error tables consist of one word per error number; each word
contains either the offset of a counted string or 0000h

Call error retrieval function with:
AX = error number
DI = offset of error table
Return: ES:DI -> error message (counted string)
Notes: this function needs to access COMMAND.COM if the messages were not
loaded into memory permanently with /MSG; the caller should assume
that the returned message will be overwritten by the next call of
the function
supported by DR-DOS 5.0
----------2F122F-----------------------------
INT 2F U - DOS 4.x internal - SET DOS VERSION NUMBER TO RETURN
AX = 122Fh
DX = DOS version number (0000h = return true DOS version)
Note: not available under DR-DOS 5.0 or 6.0
SeeAlso: INT 21/AH=30h,INT 21/AX=3306h
----------2F13-------------------------------
INT 2F U - DOS 3.2+ - SET DISK INTERRUPT HANDLER
AH = 13h
DS:DX -> interrupt handler disk driver calls on read/write
ES:BX = address to restore INT 13 to on system halt (exit from root
shell) or warm boot (INT 19)
Return: DS:DX from previous invocation of this function
ES:BX from previous invocation of this function
Notes: IO.SYS hooks INT 13 and inserts one or more filters ahead of the
original INT 13 handler. The first is for disk change detection
on floppy drives, the second is for tracking formatting calls and
correcting DMA boundary errors, the third is for working around
problems in a particular version of IBM's ROM BIOS
before the first call, ES:BX points at the original BIOS INT 13; DS:DX
also points there unless IO.SYS has installed a special filter for
hard disk reads (on systems with model byte FCh and BIOS date
"01/10/84" only), in which case it points at the special filter
most DOS 3.3+ disk access is via the vector in DS:DX, although a few
functions are still invoked via an INT 13 instruction
this is a dangerous security loophole for any virus-monitoring software
which does not trap this call (many Bulgarian viruses are known to
use it to get the original ROM entry point)
SeeAlso: INT 13/AH=01h,INT 19
----------2F1400-----------------------------
INT 2F - NLSFUNC.COM - INSTALLATION CHECK
AX = 1400h
Return: AL = 00h not installed, OK to install
01h not installed, not OK
FFh installed
Notes: called by DOS v3.3+ kernel
supported by OS/2 v1.3+ compatibility box, which always returns AL=FFh
supported by DR-DOS 5.0
documented for MS-DOS 5.0, but undocumented in prior versions
SeeAlso: AX=1401h"NLSFUNC",AX=1402h"NLSFUNC"
----------2F1400-----------------------------
INT 2F - European MSDOS 4.0 POPUP - "CheckPu" - INSTALLATION CHECK
AX = 1400h
Return: AX = FFFFh if installed
BX = maximum memory required to save screen and keyboard info
CF clear if successful
CF set on error
AX = error code
0002h invalid function
0004h unknown error
Note: the POPUP interface is used by background programs (see INT 21/AH=80h)
to communicate with the user
SeeAlso: AX=1401h"POPUP",AX=1402h"POPUP",AX=1403h"POPUP"
----------2F1401-----------------------------
INT 2F U - NLSFUNC.COM - CHANGE CODE PAGE
AX = 1401h
DS:SI -> internal code page structure (see below)
BX = new code page
DX = country code???
Return: AL = status
00h successful
else DOS error code
Note: called by DOS v3.3+ kernel
SeeAlso: AX=1400h"NLSFUNC",AX=1402h"NLSFUNC",INT 21/AH=66h

Format of DOS 3.30 internal code page structure:
Offset Size Description
00h 8 BYTEs ???
08h 64 BYTEs name of country information file
48h WORD system code page
4Ah WORD number of supported subfunctions
4Ch 5 BYTEs data to return for INT 21/AX=6502h
51h 5 BYTEs data to return for INT 21/AX=6504h
56h 5 BYTEs data to return for INT 21/AX=6505h
5Bh 5 BYTEs data to return for INT 21/AX=6506h
60h 41 BYTEs data to return for INT 21/AX=6501h
----------2F1401-----------------------------
INT 2F - European MSDOS 4.0 POPUP - "PostPu" - OPEN/CLOSE POPUP SCREEN
AX = 1401h
DL = function (00h open, 01h close)
DH = wait flag
00h block until screen opens
01h return error if screen is not available
02h urgent--always open screen immediately
Return: CF clear if successful
BX = amount of memory needed to save screen and keyboard info,
0000h if default save location can be used (only if DH was 02h)
CF set on error
Note: the application using the screen is frozen until the popup screen is
closed
SeeAlso: AX=1400h"POPUP",AX=1402h"POPUP",AX=1403h"POPUP"
----------2F1402-----------------------------
INT 2F U - NLSFUNC.COM - GET COUNTRY INFO
AX = 1402h
BP = subfunction (same as AL for INT 21/AH=65h)
BX = code page
DX = country code
DS:SI -> internal code page structure (see AX=1401h)
ES:DI -> user buffer
CX = size of user buffer
Return: AL = status
00h successful
else DOS error code
Notes: called by DOS v3.3+ kernel on INT 21/AH=65h
code page structure apparently only needed for COUNTRY.SYS pathname
SeeAlso: AX=1401h"NLSFUNC",AX=1403h"NLSFUNC",AX=1404h,INT 21/AH=65h
----------2F1402-----------------------------
INT 2F - European MSDOS 4.0 POPUP - "SavePu" - SAVE POPUP SCREEN
AX = 1402h
ES:DI -> save buffer (0000h:0000h for default buffer in POPUP)
Return: CF clear if successful
CF set on error
AX = error code
0001h process does not own screen
0004h unknown error
0005h invalid pointer
SeeAlso: AX=1400h"POPUP",AX=1401h"POPUP",AX=1403h"POPUP"
----------2F1403-----------------------------
INT 2F U - NLSFUNC.COM - SET COUNTRY INFO
AX = 1403h
DS:SI -> internal code page structure (see AX=1401h)
BX = code page
DX = country code
Return: AL = status
???
Note: called by DOS v3.3+ kernel on INT 21/AH=38h
SeeAlso: AX=1402h"NLSFUNC",AX=1404h,INT 21/AH=38h"SET"
----------2F1403-----------------------------
INT 2F - European MSDOS 4.0 POPUP - "RestorePu" - RESTORE SCREEN
AX = 1403h
ES:DI -> buffer containing saved screen
(0000h:0000h for default buffer in POPUP)
Return: CF clear if successful
CF set on error
AX = error code (see AX=1402h"POPUP")
SeeAlso: AX=1400h"POPUP",AX=1401h"POPUP",AX=1402h"POPUP"
----------2F1404-----------------------------
INT 2F U - NLSFUNC.COM - GET COUNTRY INFO
AX = 1404h
BX = code page
DX = country code
DS:SI -> internal code page structure (see AX=1401h)
ES:DI -> user buffer
Return: AL = status
???
Notes: called by DOS v3.3+ kernel on INT 21/AH=38h
code page structure apparently only needed for COUNTRY.SYS pathname
SeeAlso: AX=1402h,AX=1403h,INT 21/AH=38h"GET"
----------2F14FE-----------------------------
INT 2F U - DR-DOS 5.0 NLSFUNC - ???
AX = 14FEh
DI = ???
???
Return: ???
Note: DR-DOS 5.0 NLSFUNC returns CF set and AX=0001h if AL was not 00h, FEh,
or FFh on entry.
SeeAlso: AX=14FFh
----------2F14FF-----------------------------
INT 2F U - DR-DOS 5.0 NLSFUNC - ???
AX = 14FFh
???
Return: ???
Note: DR-DOS 5.0 NLSFUNC returns CF set and AX=0001h if AL was not 00h, FEh,
or FFh on entry.
SeeAlso: AX=14FEh
----------2F1500-----------------------------
INT 2F - DOS 4.00 GRAPHICS.COM - INSTALLATION CHECK
AX = 1500h
Return: AX = FFFFh
ES:DI -> ??? (graphics data?)
Note: this installation check conflicts with the CD-ROM Extensions
installation check; moved to AX=AC00h in later versions
SeeAlso: AX=AC00h
----------2F1500BX0000-----------------------
INT 2F - CD-ROM - INSTALLATION CHECK
AX = 1500h
BX = 0000h
Return: BX = number of CD-ROM drive letters used
CX = starting drive letter (0=A:)
Notes: this installation check DOES NOT follow the format used by other
software
this installation check conflicts with the DOS 4.00 GRAPHICS.COM
installation check
SeeAlso: INT 2F/AX=D000h"Lotus"
----------2F1501-----------------------------
INT 2F - CD-ROM - GET DRIVE DEVICE LIST
AX = 1501h
ES:BX -> buffer to hold drive letter list (5 bytes per drive letter)
Return: buffer filled, for each drive letter
BYTE subunit number in driver
DWORD address of device driver header
----------2F1502-----------------------------
INT 2F - CD-ROM - GET COPYRIGHT FILE NAME
AX = 1502h
ES:BX -> 38-byte buffer for name of copyright file
CX = drive number (0=A:)
Return: CF set if drive is not a CD-ROM drive
AX = 15 (invalid drive)
CF clear if successful
SeeAlso: AX=1503h
----------2F1503-----------------------------
INT 2F - CD-ROM - GET ABSTRACT FILE NAME
AX = 1503h
ES:BX -> 38-byte buffer for name of abstract file
CX = drive number (0=A:)
Return: CF set if drive is not a CD-ROM drive
AX = 15 (invalid drive)
CF clear if successful
SeeAlso: AX=1502h
----------2F1504-----------------------------
INT 2F - CD-ROM - GET BIBLIOGRAPHIC DOC FILE NAME
AX = 1504h
ES:BX -> 38-byte buffer for name of bibliographic documentation file
CX = drive number (0=A:)
Return: CF set if drive is not a CD-ROM drive
AX = 15 (invalid drive)
CF clear if successful
----------2F1505-----------------------------
INT 2F - CD-ROM - READ VTOC
AX = 1505h
ES:BX -> 2048-byte buffer
CX = drive number (0=A:)
DX = sector index (0=first volume descriptor,1=second,...)
Return: CF set on error
AX = error code (15=invalid drive,21=not ready)
CF clear if successful
AX = volume descriptor type (1=standard,FFh=terminator,0=other)
----------2F1506-----------------------------
INT 2F - CD-ROM - TURN DEBUGGING ON
AX = 1506h
BX = debugging function to enable
Note: reserved for development
SeeAlso: AX=1507h
----------2F1507-----------------------------
INT 2F - CD-ROM - TURN DEBUGGING OFF
AX = 1507h
BX = debugging function to disable
Note: reserved for development
SeeAlso: AX=1506h
----------2F1508-----------------------------
INT 2F - CD-ROM - ABSOLUTE DISK READ
AX = 1508h
ES:BX -> buffer
CX = drive number (0=A:)
SI:DI = starting sector number
DX = number of sectors to read
Return: CF set on error
AL = error code (15=invalid drive,21=not ready)
CF clear if successful
SeeAlso: AX=1509h
----------2F1509-----------------------------
INT 2F - CD-ROM - ABSOLUTE DISK WRITE
AX = 1509h
ES:BX -> buffer
CX = drive number (0=A:)
SI:DI = starting sector number
DX = number of sectors to write
Note: corresponds to INT 26h and is currently reserved and nonfunctional
SeeAlso: AX=1508h
----------2F150A-----------------------------
INT 2F - CD-ROM - RESERVED
AX = 150Ah
----------2F150B-----------------------------
INT 2F - CD-ROM v2.00+ - DRIVE CHECK
AX = 150Bh
CX = drive number (0=A:)
Return: BX = ADADh if MSCDEX.EXE installed
AX = 0000h if drive not supported
nonzero if supported
SeeAlso: AX=150Dh
----------2F150C-----------------------------
INT 2F - CD-ROM v2.00+ - GET MSCDEX.EXE VERSION
AX = 150Ch
Return: BH = major version
BL = minor version
Note: MSCDEX.EXE versions prior to 2.00 return BX=0
----------2F150D-----------------------------
INT 2F - CD-ROM v2.00+ - GET CD-ROM DRIVE LETTERS
AX = 150Dh
ES:BX -> buffer for drive letter list (1 byte per drive)
Return: buffer filled with drive numbers (0=A:). Each byte corresponds
to the drive in the same position for function 1501h
SeeAlso: AX=150Bh
----------2F150E-----------------------------
INT 2F - CD-ROM v2.00+ - GET/SET VOLUME DESCRIPTOR PREFERENCE
AX = 150Eh
BX = subfunction
00h get preference
DX = 0000h
Return: DX = preference settings
01h set preference
DH = volume descriptor preference
01h = primary volume descriptor
02h = supplementary volume descriptor
DL = supplementary volume descriptor preference
01h = shift-Kanji
CX = drive number (0=A:)
Return: CF set on error
AX = error code (15=invalid drive,1=invalid function)
CF clear if successful
----------2F150F-----------------------------
INT 2F - CD-ROM v2.00+ - GET DIRECTORY ENTRY
AX = 150Fh
CL = drive number (0=A:)
CH bit 0 = copy flag
clear if direct copy
set if copy to structure which removed ISO/High Sierra diffs
ES:BX -> ASCIZ path name
SI:DI -> buffer for directory entry (see below)
minimum 255 bytes for direct copy
Return: CF set on error
AX = error code
CF clear if succesful
AX = disk format (0=High Sierra,1=ISO 9660)

Format of directory entry (direct copy):
Offset Size Description
00h BYTE length of directory entry
01h BYTE length of XAR in Logical Block Numbers
02h DWORD LBN of data, Intel (little-endian) format
06h DWORD LBN of data, Motorola (big-endian) format
0Ah DWORD length of file, Intel format
0Eh DWORD length of file, Motorola format
---High Sierra---
12h 6 BYTEs date and time
18h BYTE bit flags
19h BYTE reserved
---ISO 9660---
12h 7 BYTEs date and time
19h BYTE bit flags
---both formats---
1Ah BYTE interleave size
1Bh BYTE interleave skip factor
1Ch WORD volume set sequence number, Intel format
1Eh WORD volume set sequence number, Motorola format
20h BYTE length of file name
21h N BYTEs file name
BYTE (optional) padding if filename is odd length
N BYTEs system data

Format of directory entry (canonicalized):
Offset Size Description
00h BYTE length of XAR in Logical Block Numbers
01h DWORD Logical Block Number of file start
05h WORD size of disk in logical blocks
07h DWORD file length in bytes
0Bh 7 BYTEs date and time
12h BYTE bit flags
13h BYTE interleave size
14h BYTE interleave skip factor
15h WORD volume set sequence number
17h BYTE length of file name
18h 38 BYTEs ASCIZ filename
3Eh WORD file version number
40h BYTE number of bytes of system use data
41h 220 BYTEs system use data
----------2F1510-----------------------------
INT 2F - CD-ROM v2.10+ - SEND DEVICE DRIVER REQUEST
AX = 1510h
CX = CD-ROM drive letter (0 = A, 1 = B, etc)
ES:BX -> CD-ROM device driver request header (see AX=0802h)
----------2F1600-----------------------------
INT 2F - MS WINDOWS - WINDOWS ENHANCED MODE INSTALLATION CHECK
AX = 1600h
Return: AL = 00h if Windows 3.x enhanced mode or Windows/386 2.x not running
AL = 80h if Windows 3.x enhanced mode or Windows/386 2.x not running
AL = 01h if Windows/386 2.x running
AL = FFh if Windows/386 2.x running
AL = anything else
AL = Windows major version number >= 3
AH = Windows minor version number
Note: INT 2F/AH=16h comprises an API for non-Windows programs (DOS device
drivers, TSRs, and applications) to cooperate with multitasking
Windows/386 2.x and Windows 3.x and higher enhanced mode.
certain calls are also supported in the Microsoft 80286 DOS extender in
Windows standard mode
SeeAlso: AX=4680h
----------2F1602-----------------------------
INT 2F - MS WINDOWS/386 2.x - GET API ENTRY POINT
AX = 1602h
Return: ES:DI -> Windows/386 2.x API procedure entry point
Notes: this interface is supported in Windows 3.x only for 2.x compatibility
to get the current virtual machine (VM) ID in Windows/386 2.x:
AX = 0000h
ES:DI -> return address
JUMP to address returned from INT 2F/AX=1602h
After JUMP, at return address:
BX = current VM ID.
SeeAlso: AX=0C20h
----------2F1603-----------------------------
INT 2F - RM Nimbus MSDOS 3.3 - ???
AX = 1603h
Return: AX = 5248h ('RH')
DS:SI -> first byte after INT 2F handler in IBMBIO.COM
----------2F1605-----------------------------
INT 2F - MS WINDOWS - WINDOWS ENH MODE & 286 DOSX INIT BROADCAST
AX = 1605h
ES:BX = 0000h:0000h
DS:SI = 0000h:0000h
CX = 0000h
DX = flags
bit 0 = 0 if Windows enhanced-mode initialization
bit 0 = 1 if Microsoft 286 DOS extender initialization
bits 1-15 reserved (undefined)
DI = version number (major in upper byte, minor in lower)
Return: CX = 0000h if okay for Windows to load
CX <> 0 if Windows should not load
ES:BX -> startup info structure (see below)
DS:SI -> virtual86 mode enable/disable callback or 0000h:0000h
Notes: the Windows enhanced mode loader and Microsoft 286 DOS extender will
broadcast an INT 2F/AX=1605h call when initializing. Any DOS device
driver or TSR can watch for this broadcast and return the appropriate
values. If the driver or TSR returns CX <> 0, it is also its
responsibility to display an error message.
each handler must first chain to the prior INT 2F handler with
registers unchanged before processing the call
if the handler requires local data on a per-VM basis, it must store the
returned ES:BX in the "next" field of a startup info structure and
return a pointer to that structure in ES:BX
a single TSR may set the V86 mode enable/disable callback; if DS:SI is
already nonzero, the TSR must fail the initialization by setting CX
nonzero
SeeAlso: AX=1606h,AX=1608h,AX=4B05h

Format of Startup Information Structure:
Offset Size Description
00h 2 BYTEs major, minor version of info structure
02h DWORD pointer to next startup info structure or 0000h:0000h
06h DWORD pointer to ASCIZ name of virtual device file or 0000h:0000h
0Ah DWORD virtual device reference data (only used if above nonzero)
0Eh DWORD pointer to instance data records or 0000h:0000h

Format of one Instance Item in array:
Offset Size Description
00h DWORD address of instance data (end of array if 0000h:0000h)
04h WORD size of instance data

Virtual mode enable/disable procedure called with:
AX = 0000h disable V86 mode
AX = 0001h enable V86 mode
interrupts disabled
Return: CF set on error
CF clear if successful
interrupts disabled
----------2F1606-----------------------------
INT 2F - MS WINDOWS - WINDOWS ENH MODE & 286 DOSX EXIT BROADCAST
AX = 1606h
DX = flags
bit 0 = 0 if Windows enhanced-mode exit
bit 0 = 1 if Microsoft 286 DOS extender exit
bits 1-15 reserved (undefined)
Notes: if the init broadcast fails (AX=1605h returned CX <> 0), then this
broadcast will be issued immediately.
this call will be issued in real mode
SeeAlso: AX=1605h,AX=1609h
----------2F1607-----------------------------
INT 2F - MS WINDOWS - VIRTUAL DEVICE CALL OUT API
AX = 1607h
BX = virtual device ID (see INT 2F/AX=1684h)
CX = (usually) callout subfunction
Return: (usually) AX,BX,CX,DX,ES contain results
Notes: more of a convention than an API, this call specifies a standard
mechanism for Windows enhanced-mode virtual devices (VxD's) to talk
to DOS device drivers and TSRs
see below for details on several virtual devices
SeeAlso: AX=0C20h,AX=1605h,AX=1607h/BX=000Ch,AX=1607h/BX=0014h
SeeAlso: AX=1607h/BX=0015h,AX=1684h
----------2F1607BX000C-----------------------
INT 2F - MS WINDOWS - "VMD" VIRTUAL DEVICE API
AX = 1607h
BX = 000Ch (VxD identifier of "VMD")
Return: CX = nonzero if mouse driver already virtualized
Note: VMD (Virtual Mouse Driver) calls this and then checks whether CX is
nonzero; if yes, it will not automatically virtualize the mouse
driver. This would be used if MOUSE.COM already virtualizes
itself using the Windows API.
SeeAlso: AX=1607h/BX=0014h,AX=1607h/BX=0015h
----------2F1607BX0014-----------------------
INT 2F - MS WINDOWS - "VNETBIOS" VIRTUAL DEVICE API
AX = 1607h
BX = 0014H (VxD identifier of "VNETBIOS")
Return: ES:DI -> 128-byte table specifying VNETBIOS actions for each NetBIOS
command code (see below)
Note: VNETBIOS (Virtual NetBIOS) calls this function to determine whether
the NetBIOS has an extensions Windows should know about
SeeAlso: AX=1607h/BX=000Ch,AX=1607h/BX=0015h

Values for action code:
00h "VN_Unknown" unknown command
04h "VN_No_Map" no memory mapping necessary
08h "VN_Map_In" input buffer is quickly used, so no global mapping needed
0Ch "VN_Map_In" output buffer is quickly used, so no global mapping needed
10h "VN_Map_In_Out" buffer is quickly used, so no global mapping needed
14h "VN_Chain_Send" the chain-send command
18h "VN_Cancel" special case for cancel command
1Ch "VN_Buffer_In" buffer is incoming
20h "VN_Buffer_Out" buffer is outgoing
24h "VN_Buffer_In_Out" buffer used for both incoming and outgoing data
----------2F1607BX0015-----------------------
INT 2F - MS WINDOWS - "DOSMGR" VIRTUAL DEVICE API
AX = 1607h
BX = 0015h (VxD identifier of "DOSMGR")
CX = function
0000h query instance processing
Return: CX = state
0000h not instanced
other instanced (DOS 5.0 kernel returns 0001h)
DX = segment of DOS drivers
(unchanged if call handled by DOS 5.0)
ES:BX -> patch table (see below)
0001h set patches in DOS
DX = bit mask of patch requests
bit 0 enable critical sections
bit 1 NOP setting/checking user ID
bit 2 turn INT 21/AH=3Fh on STDIN into polling loop
bit 3 trap stack fault in "SYSINIT" to WIN386
bit 4 BIOS patch to trap "Insert disk X:" to WIN386
Return: AX = B97Ch
BX = bit mask of patches applied
DX = A2ABh
0002h remove patches in DOS (ignored by DOS 5.0 kernel)
DX = bit mask of patch requests (see function 0001h)
0003h get size of DOS data structures
DX = bit mask of request (only one bit can be set)
bit 0: Current Directory Structure size
Return: if supported request:
AX = B97Ch
CX = size in bytes of requested structure
DX = A2ABh
else:
all registers preserved
0004h determine instanced data structures
Return: AX = B97Ch if supported
DX = A2ABh if supported (DOS 5.0 kernel returns 0000h)
BX = bit mask of instanced items
bit 0: CDS
bit 1: SFT
bit 2: device list
bit 3: DOS swappable data area
0005h get device driver size
ES = segment of device driver
Return: DX:AX = 0000h:0000h on error (not dev. driver segment)
DX:AX = A2ABh:B97Ch if successful
BX:CX = size of device driver in bytes
Notes: the DOS 5.0 kernel provides these calls; earlier versions require a
separate driver
DOSMGR (DOS Manager) will check whether the OEM DOS/BIOS data has
been instanced via INT 2F/AX=1605h and will not perform its own
instancing of the normal DOS/BIOS data if so
SeeAlso: AX=1605h,AX=1607h/BX=000Ch,AX=1607h/BX=0014h,AX=1684h

Format of patch table:
Offset Size Description
00h WORD number of items in patch table
02h N WORDs offsets of ??? to be patched
----------2F1607BX22C0-----------------------
INT 2F - Rational Systems DOS/4GW - ???
AX = 1607h
BX = 22C0h
???
Return: ???
SeeAlso: INT 15/AX=BF02h,INT 15/AX=BF04h
----------2F1608-----------------------------
INT 2F - MS WINDOWS - WINDOWS ENHANCED MODE INIT COMPLETE BROADCAST
AX = 1608h
Notes: called after all installable devices have been initialized
real-mode software may be called between the Windows enhanced-mode init
call (AX=1605h) and this call; the software must detect this
situation
SeeAlso: AX=1605h,AX=1609h
----------2F1609-----------------------------
INT 2F - MS WINDOWS - WINDOWS ENHANCED MODE BEGIN EXIT BROADCAST
AX = 1609h
Note: called at the beginning of a normal exit sequence; not made in the
event of a fatal system crash
SeeAlso: AX=1606h,AX=1608h
----------2F160A-----------------------------
INT 2F - MS Windows 3.1 - IDENTIFY WINDOWS VERSION AND TYPE
AX = 160Ah
???
Return: ???
----------2F160B-----------------------------
INT 2F - MS Windows 3.1 - IDENTIFY TSRs
AX = 160Bh
???
Return: ???

Format of TSR-to-Windows communication structure:
Offset Size Description
00h DWORD pointer to next structure
04h WORD PSP segment
06h WORD API version ID (0100h)
08h WORD EXEC flags
bit 0: "WINEXEC"
bit 1: "LOADLIBRARY"
bit 2: "OPENDRIVER"
0Ah WORD "exec_cmd_show"
0Ch DWORD "exec_cmd"
10h 4 BYTEs reserved (0)
14h DWORD TSR ID block
18h DWORD TSR data block
----------2F160C-----------------------------
INT 2F - MS Windows 3.1 - DETECT ROMs
AX = 160Ch
???
Return: ???
Note: used by ROM Windows
----------2F1680-----------------------------
INT 2F - MS WINDOWS, DPMI, various - RELEASE CURRENT VIRTUAL MACHINE TIME-SLICE
AX = 1680h
Return: AL = 00h if the call is supported
AL = 80h (unchanged) if the call is not supported
Notes: programs can use this function in idle loops to enhance performance
under multitaskers; this call is supported by MS Windows 3.0, DOS 5+,
DPMI 1.0+, and will be supported in OS/2 2.0 for multitasking DOS
applications
does not block the program; it just gives up the remainder of the time
slice
should not be used by Windows-specific programs
SeeAlso: INT 15/AX=1000h,INT 15/AX=5305h,INT 21/AH=89h,INT 7A/BX=000Ah
----------2F1681-----------------------------
INT 2F - MS WINDOWS 3+ - BEGIN CRITICAL SECTION
AX = 1681h
Notes: used to prevent a task switch from occurring
should be followed by an INT 2F/AX=1682h call as soon as possible
nested calls are allowed, and must be followed by an appropriate number
of "end critical section" calls
not supported in Windows/386 2.x. Get INDOS flag with INT 21/AH=34h and
and increment by hand.
SeeAlso: AX=1682h,INT 15/AX=101Bh,INT 21/AH=34h
----------2F1682-----------------------------
INT 2F - MS WINDOWS 3+ - END CRITICAL SECTION
AX = 1682h
Notes: not supported in Windows/386 2.x. Get InDOS flag with INT 21/AH=34h
and decrement by hand, taking care not to decrement InDOS flag
through zero
SeeAlso: AX=1681h,INT 15/AX=101Ch,INT 21/AH=34h
----------2F1683-----------------------------
INT 2F - MS WINDOWS 3+ - GET CURRENT VIRTUAL MACHINE ID
AX = 1683h
Return: BX = current virtual machine (VM) ID
Notes: Windows itself currently runs in VM 1, but this can't be relied upon
VM IDs are reused when VMs are destroyed
an ID of 0 will never be returned
SeeAlso: AX=1684h,AX=1685h,AX=168Bh
----------2F1684-----------------------------
INT 2F - MS WINDOWS - GET DEVICE API ENTRY POINT
AX = 1684h
BX = virtual device (VxD) ID (see below)
ES:DI = 0000h:0000h
Return: ES:DI -> VxD API entry point, or 0:0 if the VxD does not support an API
Note: some Windows enhanced-mode virtual devices provide services that
applications can access. For example, the Virtual Display Device
(VDD) provides an API used in turn by WINOLDAP.
SeeAlso: AX=1683h

Values for VxD ID:
01h VMM Virtual Machine Manager
02h Debug
03h VPICD Virtual Prog. Interrupt Controller (PIC) Device
04h VDMAD Virtual Direct Memory Access (DMA) Device
05h VTD Virtual Timer Device
06h V86MMGR Virtual 8086 Mode Device
07h PAGESWAP Paging Device
08h Parity
09h Reboot
0Ah VDD Virtual Display Device (GRABBER)
0Bh VSD Virtual Sound Device
0Ch VMD Virtual Mouse Device
0Dh VKD Virtual Keyboard Device
0Eh VCD Virtual COMM Device
0Fh VPD Virtual Printer Device
10h VHD Virtual Hard Disk Device
11h VMCPD
12h EBIOS Reserve EBIOS page (e.g., on PS/2)
13h BIOSXLAT Map ROM BIOS API between prot & V86 mode
14h VNETBIOS Virtual NetBIOS Device
15h DOSMGR
16h WINLOAD
17h SHELL
18h VMPoll
19h VPROD
1Ah DOSNET assures network integrity across VMs
1Bh VFD Virtual Floppy Device
1Ch VDD2 Secondary display adapter
1Dh WINDEBUG
1Eh TSRLoad TSR instance utility
Note: The high bit of the VxD ID is reserved for future use. The
next 10 bits are the OEM # which is assigned by Microsoft. The
low 5 bits are the device number.

Call VTD.386 entry point with:
AX = 0000h get VTD version number
Return: AH = major version
AL = minor version
AX = 0100h get current clock tick time
Return: EDX:EAX = clock tick time in 840ns units since Windows was
started
AX = 0101h get current system time in milliseconds
Return: EAX = time in milliseconds that Windows has been running
AX = 0102h get current virtual machine time
Return: EAX = cumulative amount of time the virtual machine has
been active, in milliseconds
Note: should only be called directly when TOOLHELP.DLL TimerCount() cannot
be called
----------2F1685-----------------------------
INT 2F - MS WINDOWS - SWITCH VMs AND CALLBACK
AX = 1685h
BX = VM ID of virtual machine to switch to
CX = flags
bit 0 wait until interrupts enabled
bit 1 wait until critical section unowned
bits 2-15 reserved (zero)
DX:SI = priority boost (see VMM.INC)
ES:DI -> FAR procedure to callback
Return: CF set on error
AX = error code
01h invalid VM ID
02h invalid priority boost
03h invalid flags
CF clear if successful
event will be or has been called
Notes: some DOS devices, such as networks, need to call functions in a
specific VM. This call forces the appropriate VM to be installed.
the callback procedure must preserve all registers and return with IRET
SeeAlso: AX=1683h,INT 15/AX=1117h
----------2F1686-----------------------------
INT 2F - DOS Protected-Mode Interface - DETECT MODE
AX = 1686h
Return: AX = 0000h if operating in protected mode under DPMI (INT 31 available)
AX nonzero if in real/V86 mode or no DPMI (INT 31 not available)
SeeAlso: AX=1687h
----------2F1687-----------------------------
INT 2F - DOS Protected-Mode Interface - INSTALLATION CHECK
AX = 1687h
Return: AX = 0000h if installed
BX = flags
bit 0: 32-bit programs supported
CL = processor type (02h=80286, 03h=80386, 04h=80486)
DH = DPMI major version
DL = two-digit DPMI minor version
SI = number of paragraphs of DOS extender private data
ES:DI -> DPMI mode-switch entry point
AX nonzero if not installed
SeeAlso: AX=1686h,INT 38/AH=10h

Call mode switch entry point with:
AX = flags
bit 0: set if 32-bit program
ES = real mode segment of buffer for DPMI private data (ignored if
SI was zero)
Return: CF set on error
program still in real mode
AX = error code (DPMI 1.0+)
8011h unable to allocate all necessary descriptors
8021h 32-bit program specified, but 16-bit DPMI host
CF clear if successful
CS = 16-bit selector corresponding to real-mode CS
SS = selector corresponding to real-mode SS (64K limit)
DS = selector corresponding to real-mode DS (64K limit)
ES = selector to program's PSP (100h byte limit)
FS = GS = 0
high word of ESP = 0 if 32-bit program
program now in protected mode
Note: this entry point is only called for the initial switch to protected
mode
----------2F1688-----------------------------
INT 2F U - MS Windows 3.0, 386MAX v6.01 - GET SELECTOR TO LDT
AX = 1688h
Return: AX = status??? (0000h for 386MAX)
BX = selector for ???
----------2F1689-----------------------------
INT 2F U - MS Windows 3.0+ - KERNEL IDLE CALL
AX = 1689h
???
Return: ???
----------2F168A-----------------------------
INT 2F - DPMI 0.9+ - GET VENDOR-SPECIFIC API ENTRY POINT
AX = 168Ah
DS:(E)SI = selector:offset of ASCIZ vendor name
Return: AL = status
00h successful
ES:(E)DI -> extended API entry point
8Ah unsuccessful
Notes: the vendor name is used to determine which entry point to return; it is
case-sensitive
available in protected mode only
32-bit applications use ESI and EDI, 16-bit applications use SI and DI
this call is present but not documented for DPMI 0.9
SeeAlso: INT 31/AX=0A00h

Vendor names:
"MS-DOS" ??? and 386MAX v6.00+
"386MAX" 386MAX v6.00+
----------2F168B-----------------------------
INT 2F - MS Windows 3.1 - SET FOCUS TO SPECIFIED VIRTUAL MACHINE
AX = 168Bh
???
Return: ???
SeeAlso: AX=1683h
----------2F168C-----------------------------
INT 2F - MS Windows 3.1 - RESTART COMMAND
AX = 168Ch
???
Return: ???
Note: WIN.COM executes specified application
----------2F1700-----------------------------
INT 2F - MS WINDOWS "WINOLDAP" - IDENTIFY WinOldAp VERSION
AX = 1700h
Return: AX = 1700h if this version of WINOLDAP doesn't support clipboard
AX <> 1700h
AL = WINOLDAP major version
AH = WINOLDAP minor version
Notes: WinOldAp (WINOLDAP.MOD) is a Microsoft Windows extension supporting
"old" (character-mode) application access to Dynamic Data Exchange,
menus, and the Windows clipboard.
this installation check DOES NOT follow the format used by other
software
----------2F1701-----------------------------
INT 2F - MS WINDOWS "WINOLDAP" - OPEN CLIPBOARD
AX = 1701h
Return: AX <> 0 success
AX = 0 clipboard is already open
----------2F1702-----------------------------
INT 2F - MS WINDOWS "WINOLDAP" - EMPTY CLIPBOARD
AX = 1702h
Return: AX <> 0 clipboard has been emptied
AX = 0 failure
----------2F1703-----------------------------
INT 2F - MS WINDOWS "WINOLDAP" - SET CLIPBOARD DATA
AX = 1703h
DX = clipboard format supported by WinOldAp:
01h text
02h bitmap
03h metafile picture
04h SYLK
05h DIF
06h TIFF
07h OEM text
ES:BX -> data (see below)
SI:CX = size of data
Return: AX <> 0 data copied into the Clipboard
AX = 0 failure

Format of bitmap:
Offset Size Description
00h WORD type (0000h)
02h WORD width of bitmap in pixels
04h WORD height of bitmap in pixels
06h WORD bytes per line
08h BYTE number of color planes
09h BYTE number of adjacent color bits in pixel
0Ah DWORD pointer to start of data
0Eh WORD width in 0.1mm units
10h WORD height in 0.1mm units
12h N BYTEs bitmap data

Format of metafile picture:
Offset Size Description
00h WORD mapping mode
02h WORD X extent
04h WORD Y extent
06h WORD picture data
----------2F1704-----------------------------
INT 2F - MS WINDOWS "WINOLDAP" - GET CLIPBOARD DATA SIZE
AX = 1704h
DX = clipboard format supported by WinOldAp (see AX=1703h)
Return: DX:AX = size of data in bytes, including any headers
Failure: DX:AX = 0 no data in this format in the Clipboard
----------2F1705-----------------------------
INT 2F - MS WINDOWS "WINOLDAP" - GET CLIPBOARD DATA
AX = 1705h
DX = clipboard format supported by WinOldAp (see AX=1703h)
ES:BX -> buffer
Return: AX <> 0 success
AX = 0 error, or no data in this format in Clipboard
----------2F1708-----------------------------
INT 2F - MS WINDOWS "WINOLDAP" - CloseClipboard
AX = 1708h
Return: AX <> 0 success
AX = 0 failure
----------2F1709-----------------------------
INT 2F - MS WINDOWS "WINOLDAP" - COMPACT CLIPBOARD
AX = 1709h
SI:CX = desired size in bytes
Return: DX:AX = number of bytes in largest block of free memory
Note: WinOldAp is responsible for including the size of any headers
----------2F170A-----------------------------
INT 2F - MS WINDOWS "WINOLDAP" - GET DEVICE CAPABILITIES
AX = 170Ah
DX = GDI information index
00h device driver version
02h device classification
04h width in mm
06h height in mm
08h width in pixels
0Ah height in pixels
0Ch bits per pixel
0Eh number of bit planes
10h number of brushes supported by device
12h number of pens supported by device
14h number of markers supported by device
16h number of fonts supported by device
18h number of colors
1Ah size required for device descriptor
1Ch curve capabilities
1Eh line capabilities
20h polygon capabilities
22h text capabilities
24h clipping capabilities
26h bitblt capabilities
28h X aspect
2Ah Y aspect
2Ch length of hypotenuse of aspect
58h logical pixels per inch of width
5Ah logical pixels per inch of height
Return: AX = integer value of the desired item
device classification
00h vector plotter
01h raster display
02h raster printer
03h raster camera
04h character-stream, PLP
05h Metafile, VDM
06h display-file
curve capabilities
bit 0 circles
bit 1 pie wedges
bit 2 chord arcs
bit 3 ellipses
bit 4 wide lines
bit 5 styled lines
bit 6 wide styled lines
bit 7 interiors
line capabilities
bit 1 polylines
bit 2 markers
bit 3 polymarkers
bit 4 wide lines
bit 5 styled lines
bit 6 wide styled lines
bit 7 interiors
polygon capabilities
bit 0 polygons
bit 1 rectangles
bit 2 trapezoids
bit 3 scanlines
bit 4 wide borders
bit 5 styled borders
bit 6 wide styled borders
bit 7 interiors
text capabilities
bit 0 output precision character
bit 1 output precision stroke
bit 2 clippping precision stroke
bit 3 90-degree character rotation
bit 4 arbitrary character rotation
bit 5 independent X and Y scaling
bit 6 double-size
bit 7 integer scaling
bit 8 continuous scaling
bit 9 bold
bit 10 italic
bit 11 underline
bit 12 strikeout
bit 13 raster fonts
bit 14 vector fonts
bit 15 reserved
clipping capabilities
00h none
01h clipping to rectangles
raster capabilities
bit 0 simple bitBLT
bit 1 device requires banding support
bit 2 device requires scaling support
bit 3 supports >64K bitmap
Note: This function returns the device-capability bits for the given display
----------2F1900-----------------------------
INT 2F U - DOS 4.x only SHELLB.COM - INSTALLATION CHECK
AX = 1900h
Return: AL = 00h not installed
FFh installed
----------2F1901BL00-------------------------
INT 2F U - DOS 4.x only SHELLB.COM - SHELLC.EXE INTERFACE
AX = 1901h
BL = 00h if SHELLC transient
01h if SHELLC resident
DS:DX -> far call entry point for resident SHELLC.EXE
Return: ES:DI -> SHELLC.EXE workspace within SHELLB.COM
Note: SHELLB.COM and SHELLC.EXE are parts of the DOS 4.x shell
----------2F1902-----------------------------
INT 2F U - DOS 4.x only SHELLB.COM - COMMAND.COM INTERFACE
AX = 1902h
ES:DI -> ASCIZ full filename of current batch file, with at least the
final filename element uppercased
DS:DX -> buffer for results
Return: AL = 00h failed, either
(a) final filename element quoted at ES:DI does not match
identity of shell batch file quoted as parameter of most
recent call of SHELLB command, or
(b) no more Program Start Commands available.
AL= FFh success, then:
memory at DS:[DX+1] onwards filled as:
DX+1: BYTE count of bytes of PSC
DX+2: N BYTEs Program Start Command text
BYTE 0Dh terminator
Explanation: COMMAND.COM executes the result of this call in preference to
reading a command from a batch file. Thus the batch file does not
advance in execution for so long as SHELLB provides PSCs from its
workspace. The PSCs are planted in SHELLB workspace by SHELLC, the user
menu interface. The final PSC of a sequence is finished with a
GOTO COMMON, which causes a loop back in the batch file which called
SHELLC so as to execute SHELLC again. The check on batch file name
permits PSCs to CALL nested batch files while PSCs are still stacked
up for subsequent execution.
----------2F1903-----------------------------
INT 2F U - DOS 4.x only SHELLB.COM - COMMAND.COM interface
AX = 1903h
ES:DI -> ASCIZ batch file name as for AX=1902h
Return: AL = FFh if quoted batch file name matches last SHELLB parameter
AL = 00h if it does not
----------2F1904-----------------------------
INT 2F U - DOS 4.x only SHELLB.COM - SHELLB transient to TSR intrface
AX = 1904h
Return: ES:DI -> name of current shell batch file:
WORD number of bytes of name following
BYTEs (8 max) uppercase name of shell batch file
----------2F1A00-----------------------------
INT 2F - DOS 4+ ANSI.SYS - INSTALLATION CHECK
AX = 1A00h
Return: AL = FFh if installed
Notes: AVATAR.SYS also responds to this call
documented for DOS 5+, but undocumented for DOS 4.x
----------2F1A00BX4156-----------------------
INT 2F - AVATAR.SYS - INSTALLATION CHECK
AX = 1A00h
BX = 4156h ('AV')
CX = 4154h ('AT')
DX = 4152h ('AR')
Return: AL = FFh if installed
CF clear
BX = AVATAR protocol level supported
CX = driver type
0000h AVATAR.SYS
4456h DVAVATAR.COM inside DESQview window
DX = 0016h
Notes: AVATAR also identifies itself as ANSI.SYS if BX, CX, or DX differ from
the magic values
AVATAR.SYS is a CON replacement by George Adam Stanislav which
interprets AVATAR command codes in the same way that ANSI interprets
ANSI command codes
----------2F1A01-----------------------------
INT 2F U - DOS 4+ ANSI.SYS internal - GET/SET DISPLAY INFORMATION
AX = 1A01h
CL = function
7Fh for GET
5Fh for SET
DS:DX -> parm block as for INT 21,AX=440Ch,CX=037Fh/035Fh respectively
Return: CF set on error
AX = error code (many non-standard)
CF clear if successful
AX destroyed
Note: presumably this is the DOS IOCTL interface to ANSI.SYS
SeeAlso: AX=1A02h,INT 21/AX=440Ch
----------2F1A02-----------------------------
INT 2F U - DOS 4+ ANSI.SYS internal - MISCELLANEOUS REQUESTS
AX = 1A02h
DS:DX -> parameter block (see below)
Note: DOS 5.0 chains to previous handler if AL > 02h on call
SeeAlso: AX=1A01h

Format of parameter block:
Offset Size Description
00h BYTE subfunction
00h set/reset interlock
01h get /L flag
01h BYTE interlock state
00h=reset, 01h=set
This interlock prevents some of the ANSI.SYS post-processing
in its hook onto INT 10, AH=00h mode set
02h BYTE (returned)
00h if /L not in effect
01h if /L in effect
----------2F1A21-----------------------------
INT 2F - AVATAR.SYS - SET DRIVER STATE
AX = 1A21h (AL='!')
DS:SI -> command string with one or more state characters
CX = length of command string
Return: CF set on error (invalid subfunction)
CF clear if successful
Note: the characters in the state string are interpreted left to right, and
need not be in any particular order
SeeAlso: AX=1A3Fh

Values of state characters:
'a' activate driver
'd' disable driver
'f' use fast screen output
'g' always convert gray keys (+ and -) to function keys
'G' never convert gray keys
'l' convert gray keys only when ScrollLock active
's' use slow screen output
't' Tandy 1000 keyboard (not yet implemented)
----------2F1A3C-----------------------------
INT 2F U - AVATAR.SYS v0.11 - ???
AX = 1A3Ch
???
Return: CX = 0000h
----------2F1A3E-----------------------------
INT 2F U - AVATAR.SYS v0.11 - ???
AX = 1A3Eh
CL = ???
CH = ???
DL = ???
DH = ???
Return: CL = ???
CH = ???
DL = ???
DH = ???
----------2F1A3F-----------------------------
INT 2F - AVATAR.SYS - QUERY DRIVER STATE
AX = 1A3Fh (AL='?')
ES:DI -> buffer
CX = length of buffer in bytes
Return: CF clear
CX = actual size of returned info
Note: the returned information consists of multiple letters whose meanings
are described under AX=1A21h
SeeAlso: AX=1A21h
----------2F1A42BX4156-----------------------
INT 2F - AVATAR Serial Dispatcher - INSTALL IRQ3 HANDLER
AX = 1A42h
BX = 4156h ('AV')
ES:DI -> FAR handler for serial port using IRQ3
DS = data segment needed by handler
Return: AX = 1A42h if ASD not installed
= 0000h if no more room
else handle to use when uninstalling
Notes: the handler need not save/restore registers or signal EOI to the
interrupt controller
the handler should return AX=0000h if the interrupt was meant for it,
and either leave AX unchanged or return a non-zero value otherwise
the most recently installed handler will be called first, continuing
to earlier handlers until one returns AX=0000h
SeeAlso: AX=1A43h,AX=1A62h
----------2F1A43BX4156-----------------------
INT 2F - AVATAR Serial Dispatcher - INSTALL IRQ4 HANDLER
AX = 1A43h
BX = 4156h ('AV')
ES:DI -> FAR handler for serial port using IRQ4
DS = data segment needed by handler
Return: AX = 1A43h if ASD not installed
= 0000h if no more room
else handle to use when uninstalling
Notes: (see AX=1A42h)
SeeAlso: AX=1A42h,AX=1A63h
----------2F1A44BX4156-----------------------
INT 2F - AVATAR.SYS v0.11+ - GET DATA SEGMENT
AX = 1A44h
BX = 4156h ('AV')
Return: AX = 0000h
DS = data segment
CX = size of data segment
Note: AVATAR.SYS calls this function whenever it is invoked. If each
process under a multitasker hooks this function and provides a
separate data segment, AVATAR.SYS becomes fully reentrant.
SeeAlso: AX=1A21h,AX=1A3Fh
----------2F1A52-----------------------------
INT 2F U - AVATAR.SYS v0.11 - GET ???
AX = 1A52h
CX = size of buffer
ES:DI -> buffer
Return: ??? copied into user buffer
Note: the maximum size of the data which may be copied is returned by
AX=1A72h
SeeAlso: AX=1A72h
----------2F1A53-----------------------------
INT 2F U - AVATAR.SYS v0.11 - ???
AX = 1A53h
CL = ??? (00h-05h)
???
Return: ???
----------2F1A62BX4156-----------------------
INT 2F - AVATAR Serial Dispatcher - UNINSTALL IRQ3 HANDLER
AX = 1A62h
BX = 4156h ('AV')
CX = handle for IRQ routine returned by AX=1A42h
SeeAlso: AX=1A42h,AX=1A63h
----------2F1A63BX4156-----------------------
INT 2F - AVATAR Serial Dispatcher - UNINSTALL IRQ4 HANDLER
AX = 1A63h
BX = 4156h ('AV')
CX = handle for IRQ routine returned by AX=1A43h
SeeAlso: AX=1A43h,AX=1A62h
----------2F1A72-----------------------------
INT 2F U - AVATAR.SYS v0.11 - GET ??? SIZE
AX = 1A72h
Return: CX = maximum size of ???
SeeAlso: AX=1A52h
----------2F1A7B-----------------------------
INT 2F U - AVATAR.SYS v0.11 - ???
AX = 1A7Bh
Return: AX = 0000h
CX = 0000h
----------2F1A7D-----------------------------
INT 2F U - AVATAR.SYS v0.11 - ???
AX = 1A7Dh
Return: AX = ???
----------2F1AADDX0000-----------------------
INT 2F U - AVATAR.SYS v0.11 - ???
AX = 1AADh
DX = 0000h
CX = subfunction (00h-0Ch)
???
Return: AX = 0000h if DX was nonzero
???
----------2F1B00-----------------------------
INT 2F U - DOS 4+ XMA2EMS.SYS extension internal - INSTALLATION CHECK
AX = 1B00h
Return: AL = FFh if installed
Note: XMA2EMS.SYS extension is only installed if DOS has page frames to hide.
This extension hooks onto INT 67/AH=58h and returns from that call data
which excludes the physical pages being used by DOS.
SeeAlso: AH=1Bh"FRAME INFO"
----------2F1B-------------------------------
INT 2F U - DOS 4+ XMA2EMS.SYS extension internal - GET HIDDEN FRAME INFORMATION
AH = 1Bh
AL <> 00h
DI = hidden physical page number
Return: AX = FFFFh if failed (no such hidden page)
AX = 0000h if OK, then
ES = segment of page frame
DI = physical page number
Notes: this corresponds to the data edited out of the INT 67/AH=58h call
FASTOPEN makes this call with AL = FFh
SeeAlso: AX=1B00h
----------2F2300-----------------------------
INT 2F - DR-DOS 5.0 GRAFTABL - INSTALLATION CHECK
AX = 2300h
Return: AH = FFh
Note: this installation check does not follow the usual format
SeeAlso: AH=23h
----------2F23-------------------------------
INT 2F - DR-DOS 5.0 GRAFTABL - GET GRAPHICS DATA
AH = 23h
AL nonzero
Return: AH = FFh
ES:BX -> graphics data
SeeAlso: AX=2300h
----------2F2700-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - INSTALLATION CHECK
AX = 2700h
Return: AL = 00h not installed
= FFh installed
----------2F2701-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - GET STATUS
AX = 2701h
Return: AX = maximum simultaneous tasks
BX = index into TASK_IDS of current foreground task
CX = currently-active tasks
DX = version number (DR-DOS 6.0 = 0001h)
ES:SI -> TASK_IDS
ES:DI -> name table (array of 8-byte names, NUL-terminated if <8 chars)
Notes: do not attempt to create a new task if CX == AX
the task's index is its position on the task menu, while its ID is the
position within the internal task name table
SeeAlso: AX=2714h,AX=2716h
----------2F2702-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - GET PER-TASK EMS LIMIT
AX = 2702h
Return: DX = maximum pages INT 67/AH=42h will report available
Note: TaskMAX does not limit EMS allocations other than by limiting the
amount which is reported as being available at a given time
SeeAlso: AX=2703h,INT 67/AH=42h
----------2F2703-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - SET PER-TASK EMS LIMIT
AX = 2703h
DX = maximum pages INT 67/AH=42h should report available
Return: DX = new maximum for reporting
SeeAlso: AX=2702h,INT 67/AH=42h
----------2F2704-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - REGISTER/UNREGISTER TASK MANAGER
AX = 2704h
DL = subfunction
00h unregister task manager
01h register task manager
Return: DL = status
00h registered
01h unregistered
Notes: a task manager replaces TaskMAX's menu system with its own user
interface; while one is registered, the TaskMAX hotkeys and
Ctrl-Alt-Del invoke the manager rather than the built-in menu system
unregister the task manager before terminating it
SeeAlso: AX=2705h
----------2F2705-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - ENABLE/DISABLE DIRECT SWITCHING
AX = 2705h
DL = subfunction
00h disable keystrokes for switching to next/prev/specified task
01h enable
Return: nothing
Note: should only be called by a registered task manager (see AX=2704h)
SeeAlso: AX=2704h,AX=2706h
----------2F2706-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - SWITCH TO SPECIFIED TASK
AX = 2706h
DX = task index (see AX=2701h) of task to be activated
Return: DX = task index of previously-active task
SeeAlso: AX=2705h,AX=2707h,AX=2715h
----------2F2707-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - CREATE NEW TASK
AX = 2707h
DS:DX -> ASCIZ pathname of executable
ES:BX -> parameter block (see below)
CX = number of ticks before automatic return to task manager
(0000h = run until termination or explicitly switched)
Return: DX = new task's task index (FFFFh if task terminated)
SeeAlso: AX=2706h,AX=2708h

Format of parameter block:
Offset Size Description
00h WORD reserved, should be 0000h
02h DWORD pointer to command tail to be copied into child's PSP
06h DWORD pointer to first FCB to be copied into child's PSP
0Ah DWORD pointer to second FCB to be copied into child's PSP
----------2F2708-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - DELETE TASK
AX = 2708h
DX = task index
Return: DX = FFFFh (task deleted)
Notes: this call should only be used for abnormal task termination, after
first checking for open files with AX=270Ch; should not be used
with programs that allocate EMS or XMS memory
switches to specified task first
SeeAlso: AX=2707h
----------2F2709-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - NAME TASK
AX = 2709h
DX = task index
DS:SI -> 8-byte name (8 NULs = remove name)
Return: AL = task flags
00h ID unused or task terminated
01h ID in use, task name table entry valid
81h ID in use, task name fixed
BX = task ID
ES:DI -> name in task name table (see AX=2701h)
Note: the task retains the given name until it terminates or the name is
removed by specifying a name of 8 NULs.
SeeAlso: AX=2701h,AX=2707h
----------2F270A-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - CONVERT TASK INDEX TO TASK ID
AX = 270Ah
DX = task index
Return: DX = task ID (FFFFh if index invalid)
Note: task IDs stay constant, while indexes can change when other tasks are
deleted
SeeAlso: AX=2701h,AX=270Bh
----------2F270B-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - CONVERT TASK ID TO TASK INDEX
AX = 270Bh
DX = task ID
Return: DX = task index (FFFFh if task not active)
SeeAlso: AX=270Ah
----------2F270C-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - CHECK OPEN FILES
AX = 270Ch
DX = task index
Return: AX = number of files currently open for specified task
SeeAlso: AX=2708h
----------2F270D-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - CHECK IF TASK RUNNING PRIMARY COMMAND INTERPRETER
AX = 270Dh
DX = task index
Return: DX = status
0000h if primary command interpreter (COMMAND.COM, etc.) running
0001h if not in root shell for task
Note: TaskMAX will return 0001h if the specified task has spawned another
command interpreter with AX=2707h
SeeAlso: AX=2707h,AX=270Ch
----------2F270E-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - GET/SET TEXT PASTE LEAD-IN
AX = 270Eh
CX = length of string (max 15 keystrokes, 0000h to get current string)
DS:SI -> pasting lead-in string (character/scan-code pairs)
Return: ES:DI -> current lead-in string
Note: the specified sequence of keystrokes is sent to the application before
every line of a text-mode spreadsheet paste
SeeAlso: AX=270Fh,AX=2710h,AX=2713h
----------2F270F-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - GET/SET NUMERIC PASTE LEAD-IN
AX = 270Fh
CX = length of string (max 15 keystrokes, 0000h to get current string)
DS:SI -> pasting lead-in string (character/scan-code pairs)
Return: ES:DI -> current lead-in string
Note: the specified sequence of keystrokes is sent to the application before
every number in a numeric-mode spreadsheet paste
SeeAlso: AX=270Eh,AX=2710h,AX=2711h,AX=2713h
----------2F2710-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - GET/SET PASTE LINE TERMINATOR STRING
AX = 2710h
CX = length of string (max 15 keystrokes, 0000h to get current string)
DS:SI -> pasting lead-in string (character/scan-code pairs)
Return: ES:DI -> current lead-in string
Note: the specified sequence of keystrokes is sent to the application after
every line of a spreadsheet paste operation
SeeAlso: AX=270Eh,AX=270Fh,AX=2713h
----------2F2711-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - GET/SET NUMERIC PASTE DECIMAL POINT
AX = 2711h
DX = ASCII code for separator (FFFFh to get current)
Return: DL = current separator character
SeeAlso: AX=270Fh
----------2F2712-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - INITIATE EXPORTING TASK DATA
AX = 2712h
DX = task index
----------2F2713-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - INITIATE PASTE OPERATION
AX = 2713h
DX = task index
CX = past mode
0000h alphanumeric
0001h numeric
0002h text
SeeAlso: AX=270Eh,AX=270Fh,AX=2710h,AX=2711h
----------2F2714-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - GET SWAP SPACE INFO
AX = 2714h
Return: CX = total KB of swap space
DX = available KB of swap space
SeeAlso: AX=2701h
----------2F2715-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - SWITCH TO TASK MANAGER
AX = 2715h
Return: only after calling task is again selected
SeeAlso: AX=2706h
----------2F2716-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - GET PASTE BUFFER STATUS
AX = 2716h
Return: AX = 0000h if AX=2716h,AX=2717h,AX=2718h supported
CX = bytes in paste buffer
DX = current generation number (updated after every copy operation)
SeeAlso: AX=2701h,AX=2713h,AX=2714h,AX=2717h,AX=2718h
----------2F2717-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - PASTE DATA DIRECTLY TO APPLICATION BUFFER
AX = 2717h
CX = bytes in destination buffer
ES:DI -> destination buffer
Return: AX = 0000h if function supported
CX = bytes actually copied (FFFFh if buffer too small)
DX = current generation number for paste buffer
Note: the destination buffer may be too small if another task adds more data
to the paste buffer after the AX=2716h call but before this call
SeeAlso: AX=2713h,AX=2716h,AX=2718h
----------2F2718-----------------------------
INT 2F - DR-DOS 6.0 TaskMAX - COPY DATA DIRECTLY INTO PASTE BUFFER
AX = 2718h
CX = bytes in source buffer
DS:SI -> source buffer (plain ASCII, lines terminated with CR LF)
Return: AX = 0000h if function supported
CX = bytes actually copied
DX = current generation number for paste buffer
SeeAlso: AX=2712h,AX=2716h,AX=2717h
----------2F2A-------------------------------
INT 2F - Gammafax DOS Dispatcher INTERFACE
AH = 2Ah
Note: details not available at this time
SeeAlso: AX=8000h"FaxBIOS",AX=C000h"MTEZ",AX=CB00h,AX=CBDDh,INT 66"BitFax"
----------2F3900-----------------------------
INT 2F - Kingswood TSR INTERFACE - COMPATIBILITY MODE
AX = 3900h
Return: AL = status
00h not installed
FFh one or more TSRs using this interface is installed
Note: this function is provided to that the multiplex number will appear used
to other programs
SeeAlso: AH=39h/BL=00h
----------2F39--BL00-------------------------
INT 2F - Kingswood TSR INTERFACE - INSTALLATION CHECK
AH = 39h
BL = 00h
AL = TSR ID number (01h-FFh, currently only 01h-0Eh used) (see below)
Return: AL = status
00h not installed
FFh installed
DX = segment address of resident module
Note: All of Kingswood Software's TSRs use this interface. Usually the
resident module is installed by allocating a block of upper memory,
setting its owner ID to 0008h (DOS data), and filling the MCB name
field with the TSR's name.
SeeAlso: AX=3900h,AH=39h/BL=01h

Values for TSR ID number:
01h TSR Windows
02h NOBUSY
03h CD STACK
04h DISK WATCH
05h PUSHBP
06h ALIAS
07h KEYMACRO
08h SLOWDOWN
09h ANSIGRAB
0Ah TEE
0Bh FASTMOUS
0Ch EXTWILD
0Dh BREAKOUT
0Eh STOPDISK

Format of TSR modules:
Offset Size Description
00h 4 BYTEs signature "FTSR"
04h WORD segment address of this module
06h WORD number of words to skip (usually 0000h if no PSP present)
08h N WORDs module-defined data that must be at a fixed segment offset
(usually only a PSP if file access is required)
5N BYTEs interrupt list (see below)
BYTE FFh terminator

Format of interrupt list entry:
Offset Size Description
00h BYTE interrupt number (00h-FEh)
01h WORD offset within segment of DWORD pointer to previous interrupt
03h WORD offset within segment of begin of interrupt handler code
----------2F39--BL01-------------------------
INT 2F - Kingswood TSR INTERFACE - REMOVAL CHECK
AH = 39h
BL = 01h
AL = TSR ID number (01h-FFh) (see AH=39h/BL=00h)
Return: AL = status
00h not ready to be removed
FFh resident module may be removed by deassigning the interrupts
hooked by the TSR and deallocating the TSR's memory block
AH,BX,CX,DX,ES may be destroyed
SeeAlso: AX=3900h,AH=39h/BL=00h
----------2F39-------------------------------
INT 2F - Kingswood TSR INTERFACE - APPLICATION-SPECIFIC FUNCTION CALLS
AH = 39h
BL = function number (02h-FFh)
AL = TSR ID number (01h-FFh)
CX,DX,SI,DI,DS,ES may contain parameters
Return: as appropriate for the called function
SeeAlso: AX=3900h,AH=39h/BL=00h,AX=3901h/BL=02h
----------2F3901BL02-------------------------
INT 2F - Kingswood TSR Windows - OPEN WINDOW
AX = 3901h
BL = 02h
Return: AX = error code (0000h if successful)
Notes: opens the next TSR window on top of any others. Only three
TSR windows can be opened at any one time. The three windows
are all 40x11 characters, partly overlapping.
SeeAlso: AH=39h/BL=00h,AX=3901h/BL=03h,AX=3901h/BL=05h,AX=3901h/BL=06h
----------2F3901BL03-------------------------
INT 2F - Kingswood TSR Windows - HIDE WINDOWS
AX = 3901h
BL = 03h
Return: AX = error code (0000h if successful)
Notes: Hide any visible TSR windows from view.
SeeAlso: AH=39h/BL=00h,AX=3901h/BL=02h,AX=3901h/BL=05h
----------2F3901BL04-------------------------
INT 2F - Kingswood TSR Windows - SHOW WINDOWS
AX = 3901h
BL = 04h
Return: AX = error code (0000h if successful)
Notes: Re-display all TSR windows after a HIDE WINDOWS call.
SeeAlso: AH=39h/BL=00h,AX=3901h/BL=02h,AX=3901h/BL=03h
----------2F3901BL05-------------------------
INT 2F - Kingswood TSR Windows - CLOSE WINDOW
AX = 3901h
BL = 05h
Return: AX = error code (0000h if successful)
Notes: Close the last opened TSR window.
SeeAlso: AH=39h/BL=00h,AX=3901h/BL=02h
----------2F3901BL06-------------------------
INT 2F - Kingswood TSR Windows - SET WINDOW TITLE
AX = 3901h
BL = 06h
DS:SI -> title string
Return: AX = error code (0000h if successful)
SeeAlso: AH=39h/BL=00h,AX=3901h/BL=02h
----------2F3901BL07-------------------------
INT 2F - Kingswood TSR Windows - POSITION CURSOR
AX = 3901h
BL = 07h
CH = Y coordinate (0-10)
CL = X coordinate (0-39)
Return: AX = error code (0000h if successful)
Note: the hardware cursor is always disabled when a TSR window is opened;
this call only sets a text position
SeeAlso: AH=39h/BL=00h,AX=3901h/BL=08h,AX=3901h/BL=09h
----------2F3901BL08-------------------------
INT 2F - Kingswood TSR Windows - DISPLAY STRING
AX = 3901h
BL = 08h
DS:SI -> string
Return: AX = error code (0000h if successful)
Notes: The text is not clipped.
This routine understands Tab, NewLine and Carriage Return
SeeAlso: AH=39h/BL=00h,AX=3901h/BL=07h
----------2F3901BL09-------------------------
INT 2F - Kingswood TSR Windows - SCROLL WINDOW
AX = 3901h
BL = 09h
CL = scroll direction: 00h up, FFh down, 00h clear window
Return: AX = error code (0000h if successful)
SeeAlso: AH=39h/BL=00h,AX=3901h/BL=07h
----------2F3901BL0A-------------------------
INT 2F - Kingswood TSR Windows - SOUND BEEPER
AX = 3901h
BL = 0Ah
DX = sound divisor, or 0 for silence.
(divide 1843200 by required frequency to get value for DX)
CL = sound length in 18.2 Hz clock ticks
Return: AX = error code (0000h if successful)
SeeAlso: AH=39h/BL=00h
----------2F3901BL0B-------------------------
INT 2F - Kingswood TSR Windows - ADD OR REMOVE USER
AX = 3901h
BL = 0Bh
CL = number of users increment: +1 if adding a new user
-1 if removing a user
Return: AX = error code (0000h if successful)
Note: the TSR windows resident module may only be removed when the internal
user count is zero
SeeAlso: AH=39h/BL=00h,AX=3901h/BL=02h
----------2F4000-----------------------------
INT 2F - Windows 3.x (OS/2 2.x???) - GET VIRTUAL DEVICE DRIVER (VDD) CAPABLTIES
AX = 4000h
Return: AL = 01h does not virtualize video access
02h virtualizes the video when in text mode
03h virtualizes the video when in text mode or single plane
graphics modes
04h virtualizes the video when in text mode, single plane
graphics modes, and VGA multiplane modes
FFh virtualizes the video fully
Note: this function is used by display drivers to find out what capabilities
exist for the VDD driver and also trigger then VDD driver to call
functions 4005h and 4006h. This function also gives the Video Driver
hardware access to the video registers.
----------2F4001-----------------------------
INT 2F - OS/2 compatibility box - SWITCHING DOS TO BACKGROUND
AX = 4001h
Note: called by OS/2 when the DOS box is about to be placed in the background
and the video driver should save any necessary state
SeeAlso: AX=4002h,AX=4005h
----------2F4002-----------------------------
INT 2F - OS/2 compatibility box - SWITCHING DOS TO FOREGROUND
AX = 4002h
Note: called by OS/2 when the DOS box is about to be placed in the foreground
and the video driver should restore the previously-saved state
SeeAlso: AX=4001h,AX=4006h
----------2F4003-----------------------------
INT 2F - Windows 3.x - ENTERING VIDEO DRIVER CRITICAL SECTION
AX = 4003h
Note: This critical section must be exited within 1 second.
SeeAlso: AX=4004h
----------2F4004-----------------------------
INT 2F - Windows 3.x - EXITING VIDEO DRIVER CRITICAL SECTION
AX = 4004h
SeeAlso: AX=4003h
----------2F4005-----------------------------
INT 2F - Windows 3.x - SWITCHING DOS TO BACKGROUND
AX = 4005h
Note: called by Windows when the DOS box is about to be placed in the
background and the video driver should save any necessary state
information
SeeAlso: AX=4001h,AX=4006h
----------2F4006-----------------------------
INT 2F - Windows 3.x - SWITCHING DOS TO FOREGROUND
AX = 4006h
Note: called by Windows when the DOS box is about to be placed in the
foreground and the video driver should restore any necessary state
information
SeeAlso: AX=4002h,AX=4005h
----------2F4007-----------------------------
INT 2F - Windows 3.x - ENABLE VDD TRAPPING OF VIDEO REGISTERS
AX = 4007h
----------2F4040-----------------------------
INT 2F - PharLap 286|DOS-Extender Lite v2.5 - ???
AX = 4040h
Return: BX:CX -> ???
----------2F41-------------------------------
INT 2F - LAN Manager 2.0 DOS Enhanced NETPOPUP.EXE - NETWORK POP-UP SERVICE
AH = 41h
???
Return: ???
Note: LAN Manager enhanced mode adds features beyond the standard redirector
file/printer services
SeeAlso: AX=118Ah,AH=42h,AH=4Bh
----------2F42-------------------------------
INT 2F - LAN Manager 2.0 DOS Enhanced MSRV.EXE - MESSENGER SERVICE
AH = 42h
???
Return: ???
Note: LAN Manager enhanced mode adds features beyond the standard redirector
file/printer services
SeeAlso: AX=118Ah,AH=41h,AH=4Bh
----------2F4300-----------------------------
INT 2F - EXTENDED MEMORY SPECIFICATION (XMS) - INSTALLATION CHECK
AX = 4300h
Return: AL = 80h XMS driver installed
AL <> 80h no driver
Notes: XMS gives access to extended memory and noncontiguous/nonEMS memory
above 640K
this installation check DOES NOT follow the format used by other
software
SeeAlso: AX=4310h
----------2F4310-----------------------------
INT 2F - EXTENDED MEMORY SPECIFICATION (XMS) - GET DRIVER ADDRESS
AX = 4310h
Return: ES:BX -> driver entry point
Note: HIMEM.SYS v2.77 chains to previous handler if AH is not 00h or 10h
SeeAlso: AX=4300h

Perform a FAR call to the driver entry point with AH set to the function code
AH function
00h Get XMS version number
Return: AX = XMS version (in BCD, AH=major, AL=minor)
BX = internal revision number
DX = 0001h if HMA (1M to 1M + 64K) exists
0000h if HMA does not exist
01h Request High Memory Area (1M to 1M + 64K)
DX = memory in bytes (for TSR or device drivers)
FFFFh if application program
Return: AX = 0001h success
= 0000h failure
BL = error code (80h,81h,90h,91h,92h) (see below)
02h Release High Memory Area
Return: AX = 0001h success
= 0000h failure
BL = error code (80h,81h,90h,93h) (see below)
03h Global enable A20, for using the HMA
Return: AX = 0001h success
= 0000h failure
BL = error code (80h,81h,82h) (see below)
04h Global disable A20
Return: AX = 0001h success
= 0000h failure
BL = error code (80h,81h,82h,94h) (see below)
05h Local enable A20, for direct access to extended memory
Return: AX = 0001h success
= 0000h failure
BL = error code (80h,81h,82h) (see below)
06h Local disable A20
Return: AX = 0001h success
= 0000h failure
BL = error code (80h,81h,82h,94h) (see below)
07h Query A20 state
Return: AX = 0001h enabled
= 0000h disabled
BL = error code (00h,80h,81h) (see below)
08h Query free extended memory, not counting HMA
BL = 00h (some implementations leave BL unchanged on success)
Return: AX = size of largest extended memory block in K
DX = total extended memory in K
BL = error code (00h,80h,81h,A0h) (see below)
09h Allocate extended memory block
DX = Kbytes needed
Return: AX = 0001h success
DX = handle for memory block
= 0000h failure
BL = error code (80h,81h,A0h) (see below)
0Ah Free extended memory block
DX = handle of block to free
Return: AX = 0001h success
= 0000h failure
BL = error code (80h,81h,A2h,ABh) (see below)
0Bh Move extended memory block
DS:SI -> EMM structure (see below)
Note: if either handle is 0000h, the corresponding offset is
considered to be an absolute segment:offset address in
directly addressable memory
Return: AX = 0001h success
= 0000h failure
BL = error code (80h-82h,A3h-A9h) (see below)
0Ch Lock extended memory block
DX = handle of block to lock
Return: AX = 0001h success
DX:BX = 32-bit linear address of locked block
= 0000h failure
BL = error code (80h,81h,A2h,ACh,ADh) (see below)
0Dh Unlock extended memory block
DX = handle of block to unlock
Return: AX = 0001h success
= 0000h failure
BL = error code (80h,81h,A2h,AAh) (see below)
0Eh Get handle information
DX = handle for which to get info
Return: AX = 0001h success
BH = block's lock count
BL = number of free handles left
DX = block size in K
= 0000h failure
BL = error code (80h,81h,A2h) (see below)
0Fh Reallocate extended memory block
DX = handle of block
BX = new size of block in K
Return: AX = 0001h success
= 0000h failure
BL = error code (80h,81h,A0h-A2h,ABh) (see below)
10h Request upper memory block (nonEMS memory above 640K)
DX = size of block in paragraphs
Return: AX = 0001h success
BX = segment address of UMB
DX = actual size of block
= 0000h failure
BL = error code (80h,B0h,B1h) (see below)
DX = largest available block
11h Release upper memory block
DX = segment address of UMB to release
Return: AX = 0001h success
= 0000h failure
BL = error code (80h,B2h) (see below)
12h (XMS v3.0) Reallocate upper memory block
DX = segment address of UMB to resize
BX = new size of block in paragraphs
Return: AX = 0001h success
= 0000h failure
BL = error code (80h,B0h,B2h) (see below)
34h (QEMM 5.11 only, undocumented) ???
44h (QEMM 5.11 only, undocumented) ???
88h (XMS v3.0) Query free extended memory
Return: EAX = largest block of extended memory, in K
BL = status
00h success
80h not implemented (i.e. on a 286 system)
81h VDISK detected
A0h all extended memory allocated
ECX = physical address of highest byte of memory
(valid even on error codes 81h and A0h)
EDX = total Kbytes of extended memory (0 if status A0h)
89h (XMS v3.0) Allocate any extended memory
EDX = Kbytes needed
Return: AX = 0001h success
DX = handle for allocated block (free with AH=0Ah)
= 0000h failure
BL = status (80h,81h,A0h,A1h,A2h) (see below)
8Eh (XMS v3.0) Get extended EMB handle information
DX = handle
Return: AX = 0001h success
BH = block's lock count
CX = number of free handles left
EDX = block size in K
= 0000h failure
BL = status (80h,81h,A2h) (see below)
8Fh (XMS v3.0) Reallocate any extended memory block
DX = unlocked handle
EBX = new size in K
Return: AX = 0001h success
= 0000h failure
BL = status (80h,81h,A0h-A2h,ABh) (see below)
Notes: HIMEM.SYS requires at least 256 bytes free stack space
the XMS driver need not implement functions 10h through 12h to be
considered compliant with the standard

Format of EMM structure:
Offset Size Description
00h DWORD number of bytes to move (must be even)
04h WORD source handle
06h DWORD offset into source block
0Ah WORD destination handle
0Ch DWORD offset into destination block
Notes: if source and destination overlap, only forward moves (source base
less than destination base) are guaranteed to work properly
if either handle is zero, the corresponding offset is interpreted
as a real-mode address referring to memory directly addressable
by the processor

Error codes returned in BL:
00h successful
80h function not implemented
81h Vdisk was detected
82h an A20 error occurred
8Eh a general driver error
8Fh unrecoverable driver error
90h HMA does not exist
91h HMA is already in use
92h DX is less than the /HMAMIN= parameter
93h HMA is not allocated
94h A20 line still enabled
A0h all extended memory is allocated
A1h all available extended memory handles are allocated
A2h invalid handle
A3h source handle is invalid
A4h source offset is invalid
A5h destination handle is invalid
A6h destination offset is invalid
A7h length is invalid
A8h move has an invalid overlap
A9h parity error occurred
AAh block is not locked
ABh block is locked
ACh block lock count overflowed
ADh lock failed
B0h only a smaller UMB is available
B1h no UMB's are available
B2h UMB segment number is invalid
----------2F44-------------------------------
INT 2F U - ???
AH = 44h
AL = function (at least 0Bh, 15h, 17h)
???
Return: ???
Note: called by Codeview for Windows
SeeAlso: AH=86h
----------2F4500-----------------------------
INT 2F U - Microsoft Profiler (PROF.COM/VPROD.386) - INSTALLATION CHECK
AX = 4500h
Return: AL = 01h if PROF.COM installed
AL = 02h if VPROD.386 installed
SeeAlso: AX=4501h,AX=4502h
----------2F4501-----------------------------
INT 2F U - Microsoft Profiler (PROF.COM/VPROD.386) - SETUP PROFILER
AX = 4501h
BX = CSIPS buffer size in KB (first parameter for ProfSetup)
CX = output limit in KB (second parameter for ProfSetup)
Note: this call is not supported by PROF.COM
SeeAlso: AX=4502h,AX=4503h
----------2F4502-----------------------------
INT 2F U - Microsoft Profiler (PROF.COM/VPROD.386) - SET SAMPLING RATE
AX = 4502h
BL = sampling rate for PROF.COM (0 < BL <= 13)
(01h = 8192/s, 04h = 1024/s, 08h = 32/s, 0Dh = 1/s)
CX = sampling rate for VPROD.386
Note: for PROF.COM, this programs the CMOS clock by setting BL+2 as the
low four bits of CMOS register 0Ah. The interruption rate is
1 SHL (15 - BL) per second.
SeeAlso: AX=4501h,AX=4503h
----------2F4503-----------------------------
INT 2F U - Microsoft Profiler (PROF.COM/VPROD.386) - START PROFILING
AX = 4503h
Notes: Profiling is also turned on by the key combinations
LeftShift + RightShift + Alt
LeftShift + RightShift + Ctrl
for PROF.COM, this call programs the CMOS clock by reading register
0Ch, and setting bit 6 of register 0Bh. It then makes sure that IRQ8
is unmasked
SeeAlso: AX=4504h
----------2F4504-----------------------------
INT 2F U - Microsoft Profiler (PROF.COM/VPROD.386) - STOP PROFILING
AX = 4504h
Notes: profiling is also turned off by the key combination
LeftShift + RightShift
for PROF.COM, this programs the CMOS clock by reading register 0Ch
and clearing bit 6 of register 0Bh. It then masks IRQ8.
SeeAlso: AX=4503h,AX=4505h,AX=4506h,AX=4507h
----------2F4505-----------------------------
INT 2F U - Microsoft Profiler (PROF.COM/VPROD.386) - CLEAR PROFILING DATA
AX = 4505h
SeeAlso: AX=4503h,AX=4504h,AX=4506h
----------2F4506-----------------------------
INT 2F U - Microsoft Profiler (PROF.COM/VPROD.386) - "ProfFlush"
AX = 4506h
SeeAlso: AX=4505h,AX=4507h
----------2F4507-----------------------------
INT 2F U - Microsoft Profiler (PROF.COM/VPROD.386) - "ProfFinish"
AX = 4507h
Note: this call is essentially a "ProfStop" (AX=4504h) followed by
"ProfFlush" (AX=4506h)
SeeAlso: AX=4504h,AX=4505h,AX=4506h
----------2F4508-----------------------------
INT 2F U - Microsoft Profiler (PROF.COM/VPROD.386) - ALTERNATE SEGDEBUG IFACE
AX = 4508h
BX = ordinal (or 0000h)
CX = segment
DX = instance (or 0000h)
SI = type (or 0000h)
ES:DI -> ASCIZ module name
Notes: this call is an alternate entry to the profiler's SEGDEBUG
interface, but only to function 0, for notifying the profiler of
each new segment loaded. The SHOWHITS utility then examines the
profiler's output files (CSIPS.DAT and SEGENTRY.DAT) in conjunction
with symbol files to provide information in a useful form.
this call does not have a corresponding Windows function
SeeAlso: AX=4500h
----------2F4601-----------------------------
INT 2F U - DOS 5.0 kernel - ???
AX = 4601h
Return: ???
Note: copies the MCB following the caller's PSP memory block into DOS data
segment
SeeAlso: AX=4602h
----------2F4602-----------------------------
INT 2F U - DOS 5.0 kernel - ???
AX = 4602h
Return: ???
Note: copies previously copied MCB from DOS data segment into MCB following
caller's PSP memory block
SeeAlso: AX=4601h
----------2F46-------------------------------
INT 2F U - ???
AH = 46h
AL = subfunction (03h,04h)
Return: ???
Note: these two subfunctions are called by MS Windows 3.0
----------2F4653CX0002-----------------------
INT 2F - F-PROT v1.x only - F-LOCK.EXE
AX = 4653h
CX = 0002h
BX = subfunction
0000h installation check
Return: AX = FFFFh
0001h uninstall
Return: AX,BX,ES destroyed
0002h disable (v1.08 and below only)
0003h enable (v1.08 and below only)
Note: F-LOCK is part of the F-PROT virus/trojan protection package by Fridrik
Skulason
SeeAlso: AX=4653h/CX=0003h,AX=CA00h,INT 21/AX=4BEEh
----------2F4653CX0003-----------------------
INT 2F - F-PROT v1.x only - F-XCHK.EXE
AX = 4653h
CX = 0003h
BX = subfunction
0000h installation check
Return: AX = FFFFh
0001h uninstall
Return: AX,BX,ES destroyed
Note: F-XCHK is part of the F-PROT virus/trojan protection package by Fridrik
Skulason
SeeAlso: AX=4653h/CX=0002h,AX=4653h/CX=0004h,AX=CA00h
----------2F4653CX0004-----------------------
INT 2F - F-PROT v1.x only - F-POPUP.EXE
AX = 4653h
CX = 0004h
BX = subfunction
0000h installation check
Return: AX = FFFFh
0001h uninstall
Return: AX,BX,ES destroyed
0002h disable (v1.08 and below only)
display message (v1.14+)
other registers: ???
0003h enable (v1.08 and below only)
display message (v1.14+)
other registers: ???
Return: AX = key pressed by user
Note: F-POPUP is part of the F-PROT virus/trojan protection package by
Fridrik Skulason
SeeAlso: AX=4653h/CX=0003h,AX=4653h/CX=0005h,AX=CA00h
----------2F4653CX0005-----------------------
INT 2F - F-PROT v1.x only - F-DLOCK.EXE
AX = 4653h
CX = 0005h
BX = subfunction
0000h installation check
Return: AX = FFFFh
0001h uninstall
Return: AX,BX,ES destroyed
Note: F-DLOCK is part of the F-PROT virus/trojan protection package by
Fridrik Skulason
SeeAlso: AX=4653h/CX=0004h,AX=CA00h
----------2F4680-----------------------------
INT 2F - MS Windows v3.0 - INSTALLATION CHECK
AX = 4680h
Return: AX = 0000h MS Windows 3.0 running in real (/R) or standard (/S) mode,
or DOS 5 DOSSHELL active
nonzero no Windows, Windows prior to 3.0, or Windows3 in enhanced
mode
Note: not officially documented, but Microsoft has indicated that they
intend to provide an installation check which works in all modes
SeeAlso: AX=1600h
----------2F4800-----------------------------
INT 2F - DOS v5.0 DOSKEY - INSTALLATION CHECK
AX = 4800h
Return: AL = nonzero if installed
SeeAlso: AX=4810h
----------2F4810-----------------------------
INT 2F - DOS v5.0 DOSKEY - READ INPUT LINE FROM CONSOLE
AX = 4810h
DS:DX -> line buffer (see INT 21/AH=0Ah)
Return: AX = 0000h if successful
Notes: the first byte (length) of the buffer MUST be 80h, or DOSKEY chains to
the previous handler
if the user's input is a macro name, no text is placed in the buffer
even though AX=0000h on return; the program must immediately issue
this call again to retrieve the expansion of the macro. Similarly,
if the user enters a special parameter such as $*, this call must
be repeated to retrieve the expansion; on the second call, DOSKEY
overwrites the macro name on the screen with its expansion.
SeeAlso: AX=4800h,INT 21/AH=0Ah
----------2F4A00CX0000-----------------------
INT 2F U - DOS v5.0 - SINGLE-FLOPPY LOGICAL DRIVE CHANGE NOTIFICATION
AX = 4A00h
CX = 0000h
DH = new drive number
DL = current drive number
Return: CX = FFFFh to skip "Insert diskette for drive X:" message
Note: called by MSDOS 5.00 IO.SYS just before displaying the message
"Insert diskette for drive X:" on single-floppy systems
----------2F4A01-----------------------------
INT 2F - DOS 5.0 - QUERY FREE HMA SPACE
AX = 4A01h
Return: BX = number of bytes available in HMA (0000h if DOS not using HMA)
ES:DI -> start of available HMA area (FFFFh:FFFFh if not using HMA)
Note: called by Windows 3.1 DOSX.EXE
SeeAlso: AX=4310h,AX=4A02h
----------2F4A02-----------------------------
INT 2F - DOS 5.0 - ALLOCATE HMA SPACE
AX = 4A02h
BX = number of bytes
Return: ES:DI -> start of allocated HMA block or FFFFh:FFFFh
BX destroyed
Notes: this call is not valid unless DOS is loaded in the HMA (DOS=HIGH)
called by Windows 3.1 DOSX.EXE
SeeAlso: AX=4A01h
----------2F4A05-----------------------------
INT 2F U - DOS 5.0 DOSSHELL - TASK SWITCHING API???
AX = 4A05h
SI = function
0000h reset???
0001h ???
0002h ???
0003h ???
0004h ???
BL = ???
0005h ???
0006h get ???
Return: ES:DI -> ???
0007h get ???
Return: AX = ???
0008h get ???
Return: DX:AX -> ???
0009h get ???
Return: ES = ???
000Ah ???
BL = ???
ES:DI -> ???
000Bh get ???
Return: AX = ???
000Ch ???
BL = ???
Return: DX:AX -> ???
Notes: DOSSHELL chains to the previous handler if SI is not one of the values
listed above
the DOSSWAP.EXE module calls functions 03h,04h,05h,07h,08h,09h,0Ch
the Windows 3.1 DSWAP.EXE and WSWAP.EXE task switchers use these calls
SeeAlso: AX=4B01h
----------2F4A06-----------------------------
INT 2F U - ??? - GET MEMORY SIZE
AX = 4A06h
DX = segment following last byte of conventional memory
Return: DX = segment following last byte of memory available for use by DOS
Note: called by MSDOS 5.00 IO.SYS startup code if the signature "RPL" is
present three bytes beyond the INT 2F handler; this call overrides
the value returned by INT 12
SeeAlso: INT 12
----------2F4A10-----------------------------
INT 2F - SMARTDRV v4.00+ - API
AX = 4A10h
BX = command
0000h installation check and hit ratios
Return: AX = BABEh if installed
DX:BX = cache hits
DI:SI = cache misses
CX = ???
BP = version (4.00 = 0400h)
0001h reset cache
0002h flush buffers
0003h status
BP = drive # (0=A, 1=B, etc.)
DL = subfunction
00h only get information
01h turn on read cache
02h turn off read cache
03h turn on write cache
04h turn off write cache
Return: AX = BABEh if OK
DL = status
bit 7 not cached
bit 6 write-through
bit 5 ???
bits 0-4 drive # (0=A, 1=B...)
DL = FFh if drive does not exist
Note: If the read cache is off, reads will not be cached,
but writes will continue to be cached if the write-
cache is enabled.
0004h cache size
Return: AX = ???
BX = largest number of elements
CX = size of elements in bytes
DX = number of elements under Windows
0005h double-buffer status
BP = drive # (0=A, 1=B...)
Return: AX = BABEh if double-buffered
0007h ???
Return: DI = random number???
000Ah get table pointer???
Return: ES:BX -> table of about 10 bytes or 5 words. Seems to
be words pointing to memory addresses
containing info??? (see below)
1234h signal serious error
pops up a message box saying that a serious error occurred and
to hit R to retry.
SeeAlso: INT 21/AX=4402h"SMARTDRV",INT 21/AX=4403h"SMARTDRV"

Format of data table:
Offset Size Description
00h 8 BYTEs ???
08h WORD offset of WORD containing number of elements in cache
----------2F4B-------------------------------
INT 2F - LAN Manager 2.0 DOS Enh NETWKSTA.EXE - NETWORK WORKSTATION REDIRECTOR
AH = 4Bh
???
Return: ???
Note: LAN Manager enhanced mode adds features beyond the standard redirector
file/printer services
SeeAlso: AX=118Ah,AH=41h,AH=42h
----------2F4B01-----------------------------
INT 2F - DOS v5.0 TASK SWITCHER - BUILD CALLOUT CHAIN
AX = 4B01h
CX:DX -> task switcher entry point (see AX=4B02h)
ES:BX = 0000h:0000h
Return: ES:BX -> callback info structure (see below) or 0000h:0000h
Notes: called by the task switcher
this function is hooked by clients which require notification of task
switcher activities; the call must first be passed on to the prior
handler with registers unchanged using a simulated interrupt. On
return, the client must build a callback info structure and store
the returned ES:BX in the "next" field, then return the address of
its own callback info structure.
a client program must add itself to the notification chain if it
provides services to other programs; before terminating, it must
remove itself from the chain by calling the task switcher's entry
point with AX=0005h (see AX=4B02h)
the task switcher entry point should not be saved, as it is subject to
change and will be provided on any notification call
the Windows 3.1 Standard Mode supports this API
SeeAlso: AX=4B02h

Format of callback info structure:
Offset Size Description
00h DWORD pointer to next callback info structure
04h DWORD pointer to notification function (see below)
08h DWORD reserved
0Ch DWORD address of zero-terminated list of API info structures
(see AX=4B02h)

Notification function is called with:
AX = function
0000h switcher initialization
Return: AX = 0000h if OK to load
= nonzero to abort task switcher
0001h query suspend
BX = session ID
Return: AX = 0000h if OK to switch session
= 0001h if not
0002h suspend session
BX = session ID
interrupts disabled
Return: AX = 0000h if OK to switch session
= 0001h if not
0003h activate session
BX = session ID
CX = session status flags
bit 0: set if first activation of session
bits 1-15: reserved (0)
interrupts disabled
Return: AX = 0000h
0004h session active
BX = session ID
CX = session status flags
bit 0: set if first activation of session
bits 1-15: reserved (0)
Return: AX = 0000h
0005h create session
BX = session ID
Return: AX = 0000h if OK to create session
= 0001h if not
0006h destroy session
BX = session ID
Return: AX = 0000h
0007h switcher termination
BX = flags
bit 0: set if calling switcher is only switcher loaded
bits 1-15: reserved (0)
Return: AX = 0000h
ES:DI -> task switcher entry point (see AX=4B02h)
Notes: function 0000h is generally called by the program which controls or
invokes the task switcher, rather than by the task switcher itself;
the entry point supplied to this function is not necessarily the
entry point to the task switcher itself, and may be 0000h:0000h. If
any client indicates that loading is not possible, all clients will
be called with function 0007h; thus it is possible for a client to
receive a termination notice without a corresponding initialization
notice.
except for functions 0002h and 0003h, the notification handler is
called with interrupts enabled and may make any INT 21h function
call; interrupts must not be enabled in functions 0002h and 0003h
function 0007h may be called with ES:DI = 0000h:0000h if the entry
point is no longer valid
----------2F4B02BX0000-----------------------
INT 2F - DOS v5.0 TASK SWITCHER - INSTALLATION CHECK
AX = 4B02h
BX = 0000h
ES:DI = 0000h:0000h
Return: ES:DI = 0000h:0000h if task switcher not loaded
ES:DI -> task switcher entry point (see below) if loaded
AX = 0000h
Note: the returned entry point is that for the most-recently loaded task
switcher; the entry points for prior task switchers may be determined
with the "get version" call (see below)
SeeAlso: AX=4A05h,AX=4B03h

Call task switcher entry point with:
AX = 0000h get version
Return: CF clear if successful
AX = 0000h
ES:BX -> task switcher version struct (see below)
CF set if unsupported function
AX = 0001h test memory region
ES:DI -> first byte to be tested
CX = size of region to test
Return: CF clear if successful
AX = memory type of tested region
0000h global
0001h global and local
0002h local (replaced on session switch)
CF set if unsupported function
AX = 0002h suspend switcher
ES:DI -> new task switcher's entry point
Return: CF clear if successful
AX = state
0000h switcher has been suspended
0001h switcher not suspended, new switcher must
abort
0002h switcher not suspended, but new switcher
may run anyway
CF set if unsupported function
AX = 0003h resume switcher
ES:DI -> new task switcher's entry point
Return: CF clear if successful
AX = 0000h
CF set if unsupported function
AX = 0004h hook notification chain
ES:DI -> callback info structure to be added to chain
(see AX=4B01h)
Return: CF clear if successful
AX = 0000h
CF set if unsupported function
AX = 0005h unhook notification chain
ES:DI -> callback info structure to be removed from chain
(see AX=4B01h)
Return: CF clear if successful
AX = 0000h
CF set if unsupported function
AX = 0006h query API support
BX = asynchronous API identifier
Return: CF clear if successful
AX = 0000h
ES:BX -> API info structure (see below) for the
client which provides the highest
level of
CF set if unsupported function

Format of task switcher version structure:
Offset Size Description
00h WORD major version of supported protocol (current protocol is 1.0)
02h WORD minor version of supported protocol
04h WORD major version of task switcher
06h WORD minor version of task switcher
08h WORD task switcher ID (see AX=4B03h)
0Ah WORD operation flags
bit 0: set if task switcher disabled
bits 1-15: reserved (0)
0Ch DWORD pointer to ASCIZ task switcher name
("MS-DOS Shell Task Switcher" for DOSSHELL task switcher)
10h DWORD pointer to previous task switcher's entry point or 0000h:0000h

Format of API info structure:
Offset Size Description
00h WORD size of structure in bytes (000Ah)
02h WORD API identifier
0001h NetBIOS
0002h 802.2
0003h TCP/IP
0004h LAN Manager named pipes
0005h Novell NetWare IPX
04h WORD major version \ of highest version of API for which the support
06h WORD minor version / level specified in the next field is provided
08h WORD support level
0001h minimal support
0002h API-level support
0003h switcher compatibility
0004h seamless compatibility
----------2F4B03-----------------------------
INT 2F - DOS v5.0 TASK SWITCHER - ALLOCATE SWITCHER ID
AX = 4B03h
ES:DI -> task switcher entry point (see AX=4B02h)
Return: AX = 0000h
BX = switcher ID (0001h-000Fh), or 0000h if no more available
Notes: if a task switcher has determined that it is the first to be loaded, it
must allocate an identifier for itself and provide this function to
all subsequent task switchers; if it is not the first to be loaded,
it must call this function to allocate an ID. The switcher ID is
used as the high four bits of all session identifiers to ensure
unique session IDs.
if no more switcher IDs are available, the new task switcher making the
call must terminate or disable itself
the task switcher providing the identifiers may call the new task
switcher's entry point as needed
this call is available from within DOSSHELL even if the task switcher
is not installed
SeeAlso: AX=4B02h,AX=4B04h
----------2F4B04-----------------------------
INT 2F - DOS v5.0 TASK SWITCHER - FREE SWITCHER ID
AX = 4B04h
BX = switcher ID
ES:DI -> task switcher entry point (see AX=4B02h)
Return: AX = 0000h
BX = status
0000h successful
other error (invalid ID or ID not allocated)
Notes: called by a task switcher when it exits, unless it was the first loaded
and is providing the support for AX=4B03h and AX=4B04h
the task switcher providing the identifiers may call the terminating
task switcher's entry point as needed
this call is available from within DOSSHELL even if the task switcher
is not installed
SeeAlso: AX=4B02h,AX=4B03h
----------2F4B05-----------------------------
INT 2F - DOS v5.0 DOSSHELL TASK SWITCHER - IDENTIFY INSTANCE DATA
AX = 4B05h
ES:BX = 0000h:0000h
CX:DX -> task switcher entry point (see AX=4B02h)
Return: ES:BX -> startup info structure (see below) or 0000h:0000h
Notes: called by task switcher
clients with instance data should hook this call, pass it through to
the previous handler with unchanged registers using a simulated
interrupt. On return, the client should create a startup info
structure (see below), store the returned ES:BX in the "next"
field, and return the address of the created structure in ES:BX
all MSDOS function calls are available from within this call
SeeAlso: AX=1605h,AX=4B02h

Format of startup info structure:
Offset Size Description
00h 2 BYTEs major, minor version of info structure (03h,00h)
02h DWORD pointer to next startup info structure or 0000h:0000h
06h DWORD 0000h:0000h (ignored)
0Ah DWORD ignored
0Eh DWORD pointer to instance data records

Format of one instance data record in array:
Offset Size Description
00h DWORD address of instance data (end of array if 0000h:0000h)
04h WORD size of instance data
----------2F53-------------------------------
INT 2F U - ???
AH = 53h
AL = subfunction (0Bh, maybe others???)
Return: ???
Note: called by MS Windows 3.1 POWER.DRV; hooked by MS Mouse driver v8.20+
SeeAlso: AH=54h,INT 33/AX=002Fh
----------2F54-------------------------------
INT 2F U - ???
AH = 54h
AL = subfunction (00h, 01h, maybe others???)
Return: ???
Note: called by MS Windows 3.1 POWER.DRV
SeeAlso: AH=53h
----------2F5453-----------------------------
INT 2F - TesSeRact RAM-RESIDENT PROGRAM INTERFACE
AX = 5453h
BX = subfunction
00h installation check
CX = 0000h
DS:SI -> 8-char blank-padded name
Return: AX = FFFFh installed
CX = ID number of already-installed copy
= anything else, not installed
CX = ID number for TSR when installed
01h get user parameters
CX = TSR ID number
Return: AX = 0000h successful
ES:BX -> user parameter block (see below)
= nonzero failed
02h check if hotkey in use
CL = scan code of hot key
Return: AX = FFFFh hot key conflicts with another TSR
otherwise safe to use the hotkey
03h replace default critical error handler
CX = TSR ID number
DS:SI -> new routine for INT 24h
Return: AX = nonzero, unable to install new handler
04h get internal data area
CX = TSR ID number
Return: AX = 0000h
ES:BX -> TSR's internal data area (see below)
= nonzero, TSR not found
05h set multiple hot keys
CX = TSR ID number
DL = number of additional hot keys to allocate
DS:SI -> table of hot keys
BYTE hotkey scan code
BYTE hotkey shift state
BYTE flag value to pass to TSR (nonzero)
Return: AX = nonzero, unable to install hot keys
06h - 0Fh reserved
10h enable TSR
CX = TSR ID number
Return: AX = nonzero, unable to enable
11h disable TSR
CX = TSR ID number
Return: AX = nonzero, unable to disable
12h unload TSR
CX = TSR ID number
Return: AX = nonzero, invalid TSR number
Note: if any interrupts used by TSR have been grabbed by
another TSR, the TesSeRact routines will wait until
it is safe to remove the indicated TSR from memory
13h restart TSR
CX = TSR ID number of TSR which was unloaded but is still in
memory
Return: AX = nonzero, unable to restart TSR
14h get status word
CX = TSR ID number
Return: AX = FFFFh invalid ID number
= other, successful
BX = bit flags
15h set status word
CX = TSR ID number
DX = new bit flags
Return: AX = nonzero, unable to set status word
16h get INDOS state at popup
CX = TSR ID number
Return: AX = 0000h successful
BX = value of INDOS flag
17h - 1Fh reserved
20h call user procedure
CX = TSR ID number
ES:DI -> user-defined data
Return: AX = 0000h successful
21h stuff keystrokes into keyboard buffer
CX = TSR ID number
DL = speed
00h stuff keystrokes only when buffer is empty
01h stuff up to four keystrokes per clock tick
02h stuff up to 15 keystrokes per clock tick
DH = scan code flag
if zero, buffer contains alternating ASCII and scan codes
if nonzero, buffer contains only ASCII codes
SI = number of keystrokes
ES:DI -> buffer to stuff
Return: AX = 0000h success
F0F0h user aborted with ^C or ^Break
other unable to stuff keystrokes
22h (v1.10) trigger popup
CX = TSR ID number
Return: AX = 0000h success, TSR will either pop up or beep to
indicate that it is unable to pop up
nonzero invalid ID number
23h (v1.10) invoke TSR's background function
CX = TSR ID number
Return: AX = 0000h success
FFFFh not safe to call background function
nonzero invalid ID number
24h - 2Fh reserved
Notes: Borland's THELP.COM popup help system for Turbo Pascal and Turbo C
(versions 1.x and 2.x only) fully supports the TesSeRact API, as
do the SWAP?? programs by Innovative Data Concepts.
AVATAR.SYS supports functions 00h and 01h (only the first three fields
of the user parameter block) using the name "AVATAR "
SeeAlso: AX=CAFEh

Format of User Parameter Block:
Offset Size Description
00h 8 BYTEs blank-padded TSR name
08h WORD TSR ID number
0Ah DWORD bitmap of supported functions
0Eh BYTE scan code of primary hotkey
00h = pop up when shift states match
FFh = no popup (if shift state also FFh)
0Fh BYTE shift state of primary hotkey
FFh = no popup (if scan code also FFh)
10h BYTE number of secondary hotkeys
11h DWORD pointer to extra hotkeys set by func 05h
15h WORD current TSR status flags
17h WORD PSP segment of TSR
19h DWORD DTA for TSR
1Dh WORD default DS for TSR
1Fh DWORD stack at popup
23h DWORD stack at background invocation

Format of TSR internal data area:
Offset Size Description
00h BYTE revision level of TesSeRact library
01h BYTE type of popup in effect
02h BYTE INT 08 occurred since last invocation
03h BYTE INT 13 occurred since last invocation
04h BYTE active interrupts
05h BYTE active soft interrupts
06h BYTE DOS major version
07h BYTE how long to wait before popping up
08h DWORD pointer to INDOS flag
0CH DWORD pointer to DOS critical error flag
10h WORD PSP segment of interrupted program
12h WORD PSP segment of prog interrupted by INT 28
14h DWORD DTA of interrupted program
18h DWORD DTA of program interrupted by INT 28
1Ch WORD SS of interrupted program
1Eh WORD SP of interrupted program
20h WORD SS of program interrupted by INT 28
22h WORD SP of program interrupted by INT 28
24h DWORD INT 24 of interrupted program
28h 3 WORDs DOS 3+ extended error info
2Eh BYTE old BREAK setting
2Fh BYTE old VERIFY setting
30h BYTE were running MS WORD 4.0 before popup
31h BYTE MS WORD 4.0 special popup flag
32h BYTE enhanced keyboard call in use
33h BYTE delay for MS WORD 4.0
11 times (for INTs 08h,09h,13h,16h,1Ch,21h,28h,2Fh,1Bh,23h, and 24h):
DWORD old interrupt vector
BYTE interrupt number
WORD offset in TesSeRact code segment of new interrupt handler
----------2F5500-----------------------------
INT 2F U - DOS v5.0 - COMMAND.COM INTERFACE
AX = 5500h
Return: AX = 0000h
DS:SI -> entry point table
Notes: used to access the shareable portion of COMMAND.COM, which may have
been moved into the HMA; only the primary COMMAND.COM retains this
portion
procedures called from a dispatcher in COMMAND's resident portion;
most assume that the segment address of the resident portion is on
the stack and are thus not of general use
----------2F6282-----------------------------
INT 2F U - PC Tools v7.0+ VDEFEND, DATAMON - SET ??? ADDRESS
AX = 6282h
CX:DX -> ??? or 0000h:0000h
DI = 0000h ???
FFFFh ???
other segment of ???
Return: BX = 0062h
Note: if CX:DX = 0000h:0000h on entry, the ??? address is not changed
(DATAMON only)
SeeAlso: INT 21/AH=FAh"VDEFEND"
----------2F6284BX0000-----------------------
INT 2F U - PC Tools v7.0+ DATAMON - INSTALLATION CHECK
AX = 6284h
BX = 0000h
CX = 0000h
Return: AX = segment of resident code
BX = 5555h
CX = 5555h
----------2F6284BX0001-----------------------
INT 2F U - PC Tools v7.0+ DATAMON - GET ???
AX = 6284h
BX = 0001h
CX = 0001h
Return: AX:BX -> ???
CX = BX
----------2F6284BX0002-----------------------
INT 2F U - PC Tools v7.0+ DATAMON - GET ???
AX = 6284h
BX = 0002h
CX = 0002h
Return: AX = ???
BX = ???
CX = AX
DX = BX
----------2F6284BX0003-----------------------
INT 2F U - PC Tools v7.0+ DATAMON - SET ??? FLAGS
AX = 6284h
BX = 0003h
CX = flags
bit 12: ???
10: ???
5: ???
3: ???
DX = flags
bit 15: ???
----------2F6400-----------------------------
INT 2F - SCRNSAV2.COM - INSTALLATION CHECK
AX = 6400h
Return: AL = 00h not installed
FFh installed
Note: SCRNSAV2.COM is a screen saver for PS/2's with VGA by Alan Ballard
SeeAlso: INT 10/AX=5555h
----------2F7000------------------------------
INT 2F - License Service API - INSTALLATION CHECK
AX = 7000h
CX = license server index (0000h to 001Fh)
Return: AL = status
00h not installed
FFh installed
Notes: The License Service API is being maintained by Microsoft but is being
supported by a large number of companies including Apple, Banyan,
DEC, HP, Lotus, Microsoft, Novell, Software Publishers Association,
and Wordperfect (not a complete list!)
Each license service provider must search for the next free index
slot to use
SeeAlso: AX=7001h,AX=7003h,AX=7004h,AX=7005h
----------2F7001------------------------------
INT 2F - License Service API - REQUEST License
AX = 7001h
CX = license server index (0000h to 001Fh)
DS:DX -> SLSREQEUST structure (see below)
Return: AX = status
0000h success
else provider error code
ES:BX = provider specific handle for the license context
SeeAlso: AX=7002h,AX=7004h,AX=7005h

Format of SLSREQUEST structure:
Offset Size Description
00h DWORD (return) status code
04h DWORD (return) handle identifying context
08h DWORD (call) address of Publisher string
0Ch DWORD (call) address of Product string
10h DWORD (call) address of Version string
14h DWORD units required
18h DWORD address of comment string
1Ch DWORD address of SLSCHALLENGE structure (see below)

Format of SLSCHALLENGE structure:
Offset Size Description
00h DWORD algorithm (currently always 1)
04h DWORD secret to be challenged (1-255)
08h DWORD size of challenge in bytes (1-255)
0Ch N BYTEs challenge data
----------2F7002------------------------------
INT 2F - License Service API - RELEASE License
AX = 7002h
CX = license server index (0000h to 001Fh)
DS:DX -> SLSRELEASE structure (see below)
ES:BX = provider specific handle for the license context
Return: AL = status
00h not installed
FFh installed
SeeAlso: AX=7001h,AX=7005h

Format of SLSRELEASE structure:
Offset Size Description
00h DWORD handle indentifying license context
04h DWORD total units consumed
08h DWORD address of comment string
----------2F7003------------------------------
INT 2F - License Service API - UPDATE
AX = 7003h
CX = license server index (0000h to 001Fh)
DS:DX -> SLSUPDATE structure
ES:BX = provider specific handle for the license context
Return: AL = status
00h not installed
FFh installed
SeeAlso: AX=7004h,AX=7005h

Format of SLSUPDATE structure:
Offset Size Description
00h DWORD (return) status code
04h DWORD (call) handle identifying license context
08h DWORD (call) total units consumed
0Ch DWORD additional units required
10h DWORD address of comment string
14h DWORD address of SLSCHALLENGE structure (see AX=7001h)
----------2F7004------------------------------
INT 2F - License Service API - GET ERROR
AX = 7004h
CX = license server index (0000h to 001Fh)
DS:DX -> SLSGETERROR structure (see below)
ES:BX = provider specific handle for the license context
Return: AL = status
00h not installed
FFh installed
SeeAlso: AX=7000h,AX=7001h

Format of SLSGETERROR structure:
Offset Size Description
00h DWORD (return) status code
04h DWORD handle identifying license context
08h DWORD error code
0Ch DWORD buffer size in bytes
10h N BYTEs data buffer
----------2F7005------------------------------
INT 2F - License Service API - QUERY License
AX = 7005h
CX = license server index (0000h to 001Fh)
DS:DX -> SLSQUERY structure (see below)
ES:BX = provider specific handle for the license context
Return: AL = status
00h not installed
FFh installed
SeeAlso: AX=7001h,AX=7002h

Format of SLSQUERY structure:
Offset Size Description
00h DWORD (return) status code
04h DWORD handle identifying license context
08h DWORD information index
0Ch DWORD buffer size in bytes
10h N BYTEs data buffer
----------2F7200-----------------------------
INT 2F - SRDISK v1.30 - INSTALLATION CHECK
AX = 7200h
Return: AL = FFh if installed
ES = segment of device driver header (see below)
Note: SRDISK is a freeware resizeable RAMdisk by Marko Kohtala

Format of device driver header:
Offset Size Description
00h 10 BYTEs same as standard device driver header (see INT 21/AH=52h)
0Ah BYTE number of subunits (drives) supported by driver
0Bh 3 BYTEs signature "SRD"
0Eh 4 BYTEs memory type string (currently only "XMS ")
12h 4 BYTEs ASCII driver version string "N.NN"
16h BYTE 00h
17h BYTE configuration format version (currently 00h)
18h WORD offset of drive configuration data
----------2F7A00-----------------------------
INT 2F - Novell NetWare - LOW-LEVEL API (IPX) INSTALLATION CHECK
AX = 7A00h
Return: AL = 00h not installed
= FFh installed
ES:DI -> FAR entry point for routines accessed exclusively
through INT 7A in NetWare versions through 2.0a. Call
with same values as INT 7A
SeeAlso: AX=7AFFh/BX=0000h,AX=D800h,INT 64"Novell",INT 7A"Novell"
----------2F7A10-----------------------------
INT 2F - Novell NetWare - TBMI v2.0 - GET TBMI STATUS
AX = 7A10h
Return: DH = major TBMI version number
DL = minor TBMI version number
CX = segment address of TBMI resident part
BX = status word of TBMI
bit 0: INT2F intercepted by TBMI
bit 1: INT7A intercepted by TBMI
bit 2: INT64 intercepted by TBMI
bits 3-14: reserved or unused ???
bit 15: outstanding task ID was detected
Note: TBMI is the Task-Switched Buffer Manager Interface
SeeAlso: AX=7A11h,AX=7A12h,AX=7A13h,AX=7A14h
----------2F7A11-----------------------------
INT 2F - Novell NetWare - TBMI v2.0 - GET INT2F HANDLERS
AX = 7A11h
Return: ES:BX -> old INT 2F handler
DS:DX -> TBMI INT 2F handler
SeeAlso: AX=7A10h,AX=7A12h,AX=7A13h
----------2F7A12-----------------------------
INT 2F - Novell NetWare - TBMI v2.0 - GET INT64 HANDLERS
AX = 7A12h
Return: ES:BX -> old INT 64 handler
DS:DX -> TBMI INT 64 handler
SeeAlso: AX=7A10h,AX=7A11h,AX=7A13h
----------2F7A13-----------------------------
INT 2F - Novell NetWare - TBMI v2.0 - GET INT7A HANDLERS
AX = 7A13h
Return: ES:BX = old INT 7A handler
DS:DX = TBMI INT 7A handler
SeeAlso: AX=7A10h,AX=7A11h,AX=7A12h
----------2F7A14-----------------------------
INT 2F - Novell NetWare - TBMI v2.0 - GET STATISTICS
AX = 7A14h
CX = statistic to retrieve
0000h available diagnostic functions???
Return: CX = maximum available function??? (000Ch for v2.0)
0001h buffers in use
Return: CX = TBMI buffers currently in use
0002h maximum buffers used
Return: CX = maximum number of buffers ever in use
0003h unavailable buffers
Return: CX = count of unavailable TBMI buffers
0004h old interrupt usage
Return: CX = TBMI accesses to intercepted old vectors INT 2F,
INT 64, and INT 7A
0005h far call usage
Return: CX = TBMI accesses to IPX/SPX far call handler (not
including internal accesses)
0006h task buffering
Return: CX = TBMI task buffering status (enabled/disabled or
disable/enable switch count???)
0007h current task ID
Return: CX = TBMI current task ID number (0000h if ???)
0008h outstanding ID count
Return: CX = number of outstanding TBMI IDs
0009h configured ECBs
Return: CX = number of TBMI Event Control Blocks configured
000Ah configured data ECBs
Return: CX = number of TBMI data ECBs configured
000Bh configured sockets
Return: CX = number of TBMI sockets configured (from NETCFG)
000Ch current sockets
Return: CX = number of TBMI sockets currently in use
SeeAlso: AX=7A10h
----------2F7A1B-----------------------------
INT 2F - Novell NetWare - TBMI v2.0 - RESERVED???
AX = 7A1Bh
Note: this call merely performs an IRET
----------2F7A80-----------------------------
INT 2F - Novell NetWare - SHELL 3.01d BROADCAST - ABNORMAL EXIT
AX = 7A80h
Return: nothing
Notes: called on abnormal exit of the NetWare shell to notify other Novell
TSRs that it is unsafe to call the shell in the future.
must be passed through so that all interested programs see the exit
on receiving this call, IPXODI clears an internal pointer to a
default value; Novell's NETBIOS.EXE clears its INT 21h pointer to
0000h:0000h and stops calling it
SeeAlso: AX=7A81h
----------2F7A81-----------------------------
INT 2F - Novell NetWare - SHELL 3.01d BROADCAST - SET SHELL INT 21 HANDLER
AX = 7A81h
CX:DX -> shell's INT 21h entry point
Return: nothing
Notes: the shell calls this function as it loads to allow interested TSRs
and drivers to make a local copy of the shell's entry point
must be passed through so that all interested programs see it
----------2F7A85-----------------------------
INT 2F - Novell NetWare - shell 3.01 - BROADCAST INFORM
AX = 7A85h
CX = broadcast server number
Return: CX = 0000h if broadcast message handled by another program
CX unchanged if broadcast not handled
----------2F7A90-----------------------------
INT 2F U - Novell NetWare - NETBIOS.EXE 3+ - INSTALLATION CHECK
AX = 7A90h
Return: AL = 00h if present
BX = ???
CX = PSP segment of NETBIOS resident code
SeeAlso: AX=7AFEh
----------2F7AFE-----------------------------
INT 2F - Novell NetWare - DOSNP.EXE - INSTALLATION CHECK
AX = 7AFEh
Return: AL = FFh if present
ES = (data???) segment of DOSNP
Program: DOSNP.EXE provides "named pipes" support for DOS workstations running
NetWare
Note: the NetWare shell calls this function and refuses to load if DOSNP is
present
SeeAlso: AX=7A90h
----------2F7AFFBX0000-----------------------
INT 2F - Novell NetWare - TBMI v2.0 - INSTALLATION CHECK???
AX = 7AFFh
BX = 0000h
CX = 4E65h ("Ne")
DX = 7457h ("tW")
ES:DI -> IPX/SPX special handler (XMS/EMS ???)
Return: AL = FFh if installed
CX = configured sockets (14h)
DS:SI -> data table ???
ES:DI -> IPX far call handler
Note: for IPX/SPX this call reportedly returns DS:DI pointing to the table
of pointers to service events queue head and tail
SeeAlso: AX=7AFFh/BX=0001h
----------2F7AFFBX0001-----------------------
INT 2F - Novell NetWare - TBMI v2.0, shell v3.01d - INSTALLATION CHECK???
AX = 7AFFh
BX = 0001h
CX = 4E65h ("Ne")
DX = 7457h ("tW")
Return: AL = FFh if installed
CX = ??? (8000h)
SI = ??? (or -> ???) (0002h)
ES:DI -> IPX far call handler
ES:DX -> 6-byte data area ???
SeeAlso: AX=7AFFh/BX=0000h
----------2F7F24-----------------------------
INT 2F - Multiplex - ???
AX = 7F24h
???
Return: ???
Note: called by PC/370, an IBM 370 emulator by Donald S. Higgins
----------2F7F26-----------------------------
INT 2F - Multiplex - ???
AX = 7F26h
???
Return: ???
Note: called by PC/370, an IBM 370 emulator by Donald S. Higgins
----------2F8000-----------------------------
INT 2F - EASY-NET - INSTALLATION CHECK
AX = 8000h
Return: AL = 00h not installed
FFh installed
Note: EASY-NET is a shareware two-machine serial-port network
----------2F8000-----------------------------
INT 2F - Nanosoft, Inc. TurboNET server - INSTALLATION CHECK
AX = 8000h
Return: AL = FFh if installed
BX = CS of resident code
CX = ??? (03FCh)
Note: TurboNET is a NetBIOS-based file redirector and server; a demonstration
version may be downloaded from Nanosoft's BBS
SeeAlso: AX=8100h
----------2F8000DX0000-----------------------
INT 2F - FaxBIOS interface - INSTALLATION CHECK
AX = 8000h
DX = 0000h
DI = 0000h
Return: AL = FFh if installed
DX:DI -> signature "FaxBiosjpc"
Note: FaxBIOS may use any multiplex number from 80h through FFh; to determine
whether it is installed, it is necessary to poll all multiplex
numbers for one which returns the above signature
SeeAlso: AH=2Ah,AX=80FBh
----------2F8001-----------------------------
INT 2F - Nanosoft, Inc. TurboNET server - ???
AX = 8001h
DS:SI -> 16-byte buffer for ???
Return: AH = status
00h successful
01h error
Note: makes NetBIOS calls
----------2F80FB-----------------------------
INT 2F - FaxBIOS interface - COMMAND SUBMISSION
AX = 80FBh
BX = function number (see below)
DX:DI -> command buffer (see below)
Return: AL = FFh if submitted OK
CX = result code (see below)
Note: FaxBIOS may use any multiplex number from 80h through FFh
SeeAlso: AX=8000h"FaxBIOS",AX=CBDDh

Values for function number:
0001h SYS_LOGIN
0002h SYS_LOGOUT
0003h SYS_GET_FAXAPP_INFO
0004h STAT_IO_GET
0005h STAT_FAXBIOS_GET
0006h PDIR_OPEN
0007h PDIR_CLOSE
0008h PDIR_READ_PERSON
0009h PDIR_PARTIAL_READ
000Ah PDIR_READ_GROUP
000Bh PDIR_READ_MEMBER_LIST
000Ch PDIR_WRITE_PERSON
000Dh PDIR_WRITE_GROUP
000Eh PDIR_DELETE_PERSON
000Fh PDIR_DELETE_GROUP
0010h PDIR_READ_GROUP_LIST
0011h PDIR_IN_GROUP
0012h PDIR_OUT_GROUP
0013h SCHED_OPEN
0014h SCHED_ADD_DEST
0015h SCHED_ADD_FILE
0016h SCHED_SET_PARAMS
0017h SCHED_CANCEL
0018h SCHED_CLOSE
0019h SLOG_OPEN
001Ah SLOG_CLOSE
001Bh SLOG_SHORT_ENV_STAT
001Ch SLOG_LONG_ENV_STAT
001Dh SLOG_DEST_STAT
001Eh SLOG_FILE_STAT
001Fh SLOG_CANCEL_ENV
0020h RLOG_OPEN
0021h RLOG_CLOSE
0022h RLOG_READ
0023h GRAPH_GET_FILE_TYPE
0024h GRAPH_EXPORT_FILE
0025h GRAPH_GET_LAYOUT_INFO
0026h GRAPH_CREATE_FILE
0027h GRAPH_CLOSE_FILE
0028h GRAPH_CREATE_PAGE
0029h GRAPH_WRITE
002Ah GRAPH_END_PAGE
002Bh GRAPH_OPEN_FILE
002Ch GRAPH_GOTO_PAGE
002Dh GRAPH_READ
002Eh IOCTL_GET
002Fh IOCTL_SET
0030h IOCTL_ANSWER_FAX
0031h IOCTL_DIAL

Values for result code:
0000h successful
0001h not prepared or servicing another client (busy)
0002h call failed due to sharing (LOCKED)
0003h logged-in client limit reached (FULL)
0004h transport denied (TRANSPORT_DENIED)
0005h not implemented (NOT_IMPLEMENTED)
0006h aborted while in progress (ABORTED)
0007h permissions denied (PERMISSION_DENIED)
0008h requested data is no longer valid (NO_LONGER_VALID)
0080h unspecified system error occurred
0081h an internal file was not found
0082h an internal file could not be created
0083h an internal file could not be opened
0084h an internal file could not be closed
0085h error occurred writing to an internal file
0086h error occurred reading from an internal file
0087h bad or corrupted file encountered
0088h an access violation occurred
0089h an internal file is empty
008Ah insufficient memory to process request
008Bh FaxBIOS was unable to issue a handle
008Ch an error internal to FaxBIOS occurred
008Dh no room on disk
0100h unspecified error accessing client file
0101h file not found
0102h creation fault
0103h open fault
0104h close fault
0105h write fault
0106h read fault
0107h file corrupted
0108h access violation
0109h empty file
0200h unspecified argument error
0201h bad function
0202h bad option
0203h bad structure size
0204h bad buffer size
0205h bad client ID
0300h unspecified error with token
0301h cover sheet token was invalid
0302h logo token was invalid
0303h signature token was invalid
0304h font token was invalid
0305h phone directory token was invalid
0306h outbound route token was invalid
0307h priority token was invalid
0308h sort token was invalid
0309h billing token was invalid
0400h unspecified handle error
0401h bad Phone Directory handle
0402h bad scheduling handle
0403h bad read send log handle
0404h bad read receive log handle
0405h bad graphics handle
0500h data passed in structure was invalid
0501h name field given is invalid
0502h phone number given is invalid
0503h poll code submitted is invalid
0504h file type constant was invalid
0505h BFT constant not defined or supported
0506h resolution not defined or supported
0507h page length not defined or supported
0508h page width not defined or supported
0509h date & time requested are ridiculous
050Ah Subject text was not an ASCIIZ string
050Bh From text was not an ASCIIZ string
050Ch requested envelope ID was not found
050Dh requested envelope ID is not valid
050Eh envelope requested was not found
050Fh destination index is out of range
0510h file index is out of range
0511h index into receive log is out of range
0512h file name specified was incomplete or invalid
0513h page selected was out of range
0514h bit width more than byte width
0515h mode for open is not defined
0516h person index is out of range
0517h person ID is out of range
0518h group index out of range or invalid
0519h group ID out of range or invalid
051Ah range of indices to read is invalid
051Bh group name given is invalid
051Ch field_to_use is badly specified
051Dh predicate invalid for field specified
0600h unspecified client procedure error
0601h device of interest is not present
0602h device of interest has been removed
0603h device of interest is not responding
0604h device of interest is disabled
0605h could not dial because device was in use
0606h maximum destination limit exceeded
0607h maximum file limit exceeded
0608h scheduling closed with no destination
0609h scheduling closed with no files or poll
060Ah scheduling closed with no parameters specified
060Bh file type specified does not match file
060Ch file type specified is not supported
060Dh file submitted is not exportable
060Eh file type specified is not imageable
060Fh error converting file
0610h envelope could not be cancelled
0611h Phone Directory is full
0612h record is already in the Phone Directory
0613h selected group in Phone Directory is full
0614h person is already in the group
0615h person is not in the group & cannot be removed
0616h a graphics file to be created already exists
0617h a grphics file to be read is empty
0618h GRAPH_CREATE_PAGE called before GRAPH_END_PAGE
0619h graph read or write attempted without goto or create
061Ah graph page contains no data
061Bh Phone Directory is already open for this client
061Ch schedule log is already open for this client
061Dh receive log is aready open for this client
061Eh Phone Directory function requires write mode
0800h denied exclusive use of the API

Format of SYS_LOGIN command buffer:
Offset Size Description
00h WORD structure size
02h WORD function number
04h WORD return code
06h WORD client ID
08h WORD API Major Version
0Ah WORD API Minor Version
0Ch DWORD reserved for manufacturer's use
10h 22 BYTEs manufacturer's ID
26h WORD highest possible device number
28h WORD maximum destinations per envelope
2Ah WORD maximum files per envelope
2Ch WORD FaxBIOS capabilities bitmap
bit 0: transmit supported
bit 1: receive supported
bit 2: IOCTL supported
bit 3: IOCTL_DIAL supported
bit 4: IOCTL_ANSWER_FAX supported
bit 5: manual transmit supported
bit 6: optional phone services supported
bit 7: canonical phone objects
bit 8: seam with next supported
2Eh DWORD T.30 capabilities bitmap
bit 0: low vertical resolution (minimum)
bit 1: high vertical resolution
bit 2: page width 107mm (4.21 in)
bit 3: page width 151mm (5.91 in)
bit 4: page width 215mm (8.46 in) (minimum)
bit 5: page width 255mm (10.04 in)
bit 6: page width 303mm (11.93 in)
bit 7: unused
bit 8: page length 297mm (11.69 in) (minimum)
bit 9: page length 364mm (14.33 in)
bit 10: page length 279mm (11 in)
bit 11: page length unlimited
bit 12: Group 4 resolution 300x300
bit 13: Group 4 resolution 400x400
bit 14: able to respond to poll from remote
bit 15: able to poll remote
bit 16: binary file transfer supported
32h WORD IPC handle
34h DWORD amount of memory needed to load
38h WORD scope (00h for public, nonzero for private)
3Ah 6 BYTEs future expansion
40h WORD structure size

Format of SYS_LOGOUT command buffer:
Offset Size Description
00h WORD structure size
02h WORD function number
04h WORD return code
06h WORD client ID
08h DWORD client tag (for client's internal use)
0Ch 6 BYTEs future expansion
12h WORD structure size

Format of SYS_GET_FAXAPP_INFO command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch 80 BYTEs FaxBIOS data
5Ch 80 BYTEs default cover
ACh 80 BYTEs default logo
FCh 80 BYTEs default signature
14Ch 80 BYTEs default font 10
19Ch 80 BYTEs default font 165
1ECh 80 BYTEs default user font
23Ch 80 BYTEs default Pdir
28Ch 80 BYTEs default sort
2DCh 10 BYTEs default bill
2E6h 10 BYTEs default route
2F0h 40 BYTEs default cover sheet form
318h 34 BYTEs valid dial characters
33Ah 6 BYTEs local country code
340h 6 BYTEs local city or area code
346h 6 BYTEs future expansion
34Ch WORD structure size

Format of STAT_IO_GET command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD device number
0Eh WORD current activity
10h WORD number of rings (if ringing)
12h WORD number of fascimiles transmitted
14h WORD number of fascimiles received
16h WORD status of last transmission
18h WORD envelope number of last transmission
1Ah WORD index of last destination in envelope
1Ch WORD status of last reception
1Eh WORD current page (if session in progress)
20h 80 BYTEs current file
70h104 BYTEs remote number
D8h 20 BYTEs last name
ECh 20 BYTEs first name
100h 32 BYTEs company name
120h 32 BYTEs notes
140h WORD current envelope ID (if sending)
142h WORD total pages in transmission (if sending)
144h 6 BYTEs future expansion
14h WORD structure size

Format of STAT_FAXBIOS_GET command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD status ID
0Eh WORD currenty FaxBIOS function number
10h WORD current Client ID being serviced
12h WORD number of things to do
14h WORD number of them done
16h WORD number of pages to do (if any)
18h WORD number of them done
1Ah WORD number of files to do
1Ch WORD number of them done
1Eh 80 BYTEs current File
6Eh WORD 0 if all devices are idle
70h WORD number of fascimiles transmitted
72h WORD number of fascimiles received
74h WORD status of last transmission in system
76h WORD envelope ID of last transmission
78h WORD index of last destination in envelope
7Ah WORD status of last reception in system
7Ch DWORD time of next transmission
80h 6 BYTEs future expansion
86h WORD structure size

Format of PDIR_OPEN command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch 80 BYTEs Phone Directory token
5Ch 80 BYTEs sort order token
ACh WORD open Mode (0 = read, 1 = write)
AEh WORD Phone Directory handle
B0h WORD number of people
B2h WORD number of groups
B4h WORD bitmap of fields supported by partial read
B6h 6 BYTEs future expansion
BCh WORD structure size

Format of PDIR_CLOSE command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD Phone Directory handle
0Eh 6 BYTEs future expansion
14h WORD structure size

Format of PDIR_READ_PERSON command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD Phone Directory handle
0Eh WORD retrieve by index
10h WORD person ID or index
12h WORD how many groups person is in
14h WORD person ID
16h 20 BYTEs last name
2Ah 20 BYTEs first name
3Eh 32 BYTEs company
5Eh 32 BYTEs notes
7Eh 6 BYTEs FAX country code
84h 6 BYTEs FAX city/area code
8Ah 14 BYTEs FAX local number
98h 14 BYTEs FAX extension
A6h 24 BYTEs reserved
BEh 6 BYTEs voice country code
C4h 6 BYTEs voice city/area code
CAh 14 BYTEs voice local number
D8h 14 BYTEs voice extension
E6h 24 BYTEs reserved
FEh 10 BYTEs outbound routing information
108h 10 BYTEs billing information, credit card etc
112h DWORD remote FAX capabilities
116h 21 BYTEs T.30 poll code of FAX number
12Bh 15 BYTEs reserved
13Ah 6 BYTEs future expansion
140h WORD structure size

Format of SCHED_OPEN, SCHED_CANCEL command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD scheduler handle
0Eh 6 BYTEs future expansion
14h WORD structure size

Format of SCHED_ADD_DEST command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD schedule handle
0Eh WORD device number if manual send wanted
10h WORD non-zero if poll desired
12h WORD person ID
14h 20 BYTEs last name
28h 20 BYTEs first name
3Ch 32 BYTEs company
5Ch 32 BYTEs notes
7Ch 6 BYTEs FAX country code
82h 6 BYTEs FAX city/area code
88h 14 BYTEs FAX local number
96h 14 BYTEs FAX extension
A4h 24 BYTEs reserved
BCh 6 BYTEs voice country code
C2h 6 BYTEs voice city/area code
C8h 14 BYTEs voice local number
D6h 14 BYTEs voice extension
E4h 24 BYTEs reserved
FCh 10 BYTEs outbound routing information
106h 10 BYTEs billing information, credit card etc
110h DWORD remote FAX capabilities
114h 21 BYTEs T.30 poll code of FAX number
129h 15 BYTEs reserved
138h 6 BYTEs future expansion
13Eh WORD structure size

Format of SCHED_ADD_FILE command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD schedule handle
0Eh WORD file type
0000h unidentified
0001h native file format
0002h ASCII
0003h FaxBIOS Tiff Class F
10h 80 BYTEs file name
60h 80 BYTEs font token
B0h WORD conversion options bitmap
B2h WORD resolution
0000h standard 98 lines per inch, 204 dpi
0001h fine 196 lines per inch, 204 dpi
0002h Group4 300 dpi
0003h Group4 400 dpi
B4h WORD page length
0000h 279 mm (11 in)
0001h 297 mm (11.69 in)
0002h 364 mm (14.33 in)
0003h unlimited
B6h WORD page width
0000h 215 mm (8.46 in)
0001h 255 mm (10.04 in)
0002h 303 mm (11.93 in)
0003h 151 mm (5.91 in)
0004h 107 mm (4.21 in)
B8h WORD binary file transfer specification
0000h only as FAX
0001h only as file (for non-faxable files)
0002h as file when possible else FAX
BAh WORD seam flag (nonzero for seam with next)
BCh WORD delete flag (nonzero to delete when done)
BEh 6 BYTEs future expansion
C4h WORD structure size

Format of SCHED_SET_PARAMS command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD scheduler handle
0Eh DWORD time to send
10h 10 BYTEs priority token
1Ch 80 BYTEs logo file token
6Ch 80 BYTEs signature file token
BCh 80 BYTEs cover page token
10Ch 40 BYTEs Subject text
134h 40 BYTEs From text
15Ch WORD user ID
15Eh 6 BYTEs future expansion
164h WORD structure size

Format of SCHED_CLOSE command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD scheduler handle
0Eh WORD envelope ID generated
10h 6 BYTEs future expansion
16h WORD structure size

Format of SLOG_OPEN, SLOG_CLOSE, RLOG_OPEN, RLOG_CLOSE command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD log handle
0Eh WORD number of entries
10h 6 BYTEs future expansion
16h WORD structure size

Format of GRAPH_GET_FILE_TYPE command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch 80 BYTEs filename
5Ch WORD file type
0000h unidentified
0001h native file format
0002h ASCII
0003h FaxBIOS Tiff Class F
5Eh WORD bitmap of supported capabilities
60h 6 BYTEs future expansion
66h WORD structure size

Format of GRAPH_CREATE_FILE command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch 80 BYTEs filename
5Ch WORD graph handle
5Eh 6 BYTEs future expansion
64h WORD structure size

Format of GRAPH_CLOSE_FILE, GRAPH_END_PAGE command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD graph handle
0Eh 6 BYTEs future expansion
14h WORD structure size

Format of GRAPH_CREATE_PAGE command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD graph handle
0Eh WORD resolution
10h WORD page width
12h 6 BYTEs future expansion
18h WORD structure size

Format of GRAPH_WRITE_PAGE command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD graph handle
0Eh DWORD pointer to storage for image
12h WORD band height in lines
14h WORD width of page image in bytes
16h WORD facsimile page width constant
18h WORD width of page image in bits
1Ah WORD number of bytes actually processed
1Ch 6 BYTEs future expansion
22h WORD structure size

Format of GRAPH_OPEN_FILE command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch 80 BYTEs filename
5Ch WORD file type
5Eh WORD graph handle
60h WORD number of pages
62h 6 BYTEs future expansion
68h WORD structure size

Format of GRAPH_GOTO_PAGE command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD graph handle
0Eh WORD page number
10h WORD vertical resolution
12h WORD page width
14h DWORD page length
18h 6 BYTEs future expansion
1Eh WORD structure size

Format of GRAPH_READ_PAGE command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD graph handle
0Eh DWORD pointer to storage for image
12h WORD band height in lines
14h WORD width of page image in bytes
16h WORD facsimile page width constant
18h WORD width of page image in bits
1Ah WORD number of bytes actually processed
1Ch 6 BYTEs future expansion
22h WORD structure size

Format of IOCTL_ANSWER_FAX command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD device number
0Eh 6 BYTEs future expansion
14h WORD structure size

Format of IOCTL_DIAL command buffer:
Offset Size Description
00h 12 BYTEs common data (see SYS_LOGOUT above)
0Ch WORD device number
0Eh 6 BYTEs country code
14h 6 BYTEs city or area code
1Ah 14 BYTEs local number
28h 14 BYTEs extension
36h 14 BYTEs reserved
4Eh 6 BYTEs future expansion
54h WORD structure size
----------2F8100-----------------------------
INT 2F U - Nanosoft, Inc. TurboNET redirector - INSTALLATION CHECK
AX = 8100h
Return: AL = FFh if installed
Note: TurboNET is a NetBIOS-based file redirector and server; a demonstration
version may be downloaded from Nanosoft's BBS
SeeAlso: AX=8000h"TurboNET"
----------2F8101-----------------------------
INT 2F U - Nanosoft, Inc. TurboNET redirector - ???
AX = 8101h
Return: AL = ???
DL = ???
----------2F8102-----------------------------
INT 2F U - Nanosoft, Inc. TurboNET redirector - ???
AX = 8102h
Return: AL = ???
DL = ???
----------2F8103-----------------------------
INT 2F U - Nanosoft, Inc. TurboNET redirector - GET MACHINE NAME???
AX = 8103h
ES:DI -> 17-byte buffer
Return: buffer filled
----------2F8104-----------------------------
INT 2F U - Nanosoft, Inc. TurboNET redirector - ???
AX = 8104h
BL = ???
BH = ???
CX = ???
DX = ???
DS:SI -> 16-byte buffer containing ???
Return: AL = 00h ???
----------2F8105-----------------------------
INT 2F U - Nanosoft, Inc. TurboNET redirector - ???
AX = 8105h
CX = ??? (don't change current value if 0000h)
DX = ??? (don't change current value if 0000h)
Return: AL = 00h successful
----------2F82-------------------------------
INT 2F U - Nanosoft, Inc. TurboNET - ???
AH = 82h
???
Return: ???
Note: called by TNR.EXE, the TurboNET redirector configuration program
SeeAlso: AX=8100h
----------2F8200-----------------------------
INT 2F - RESPLAY - SAMPLE/PLAYBACK
AX = 8200h
DX:DI -> start of sample space
CX:BX = length in bytes
Return: AX = status
1000h successful
2000h not initialized (see AX=8210h)
other RESPLAY not installed
Note: RESPLAY is a freeware sound sampling/playback utility by Mark J. Cox
SeeAlso: AX=8201h,AX=8210h
----------2F8201-----------------------------
INT 2F - RESPLAY - INSTALLATION CHECK
AX = 8201h
Return: AX = 7746h if installed
SeeAlso: AX=8202h
----------2F8202-----------------------------
INT 2F - RESPLAY - UNINSTALL
AX = 8202h
Return: AX = status
1000h successful
SeeAlso: AX=8201h
----------2F8210-----------------------------
INT 2F - RESPLAY - INITIALIZE
AX = 8210h
BL = sound device
00h printer port LPT1
01h printer port LPT2
02h prototype board at I/O address 0300h
03h printer port (alternative LPT1)
04h internal speaker
BH = sample rate in multiples of 250 Hz (14h to A0h)
CL = direction
00h playback
01h sample
Return: AX = status
1000h successful
2000h parameter out of range
other RESPLAY not installed
SeeAlso: AX=8200h
----------2F86-------------------------------
INT 2F U - ???
AH = 86h
AL = function (at least 06h and 07h)
???
Return: ???
Note: called by Codeview for Windows
SeeAlso: AH=44h
----------2F8900-----------------------------
INT 2F - WHOA!.COM - INSTALLATION CHECK
AX = 8900h
Return: AL = 00h not installed
= FFh installed
Note: WHOA!.COM is a system slow-down utility by Brad D Crandall
SeeAlso: AX=8901h,AX=8902h
----------2F8901-----------------------------
INT 2F - WHOA!.COM - UNINSTALL
AX = 8901h
Return: AL = FDh successful
= FEh error
Note: WHOA!.COM is a system slow-down utility by Brad D Crandall
SeeAlso: AX=8900h
----------2F8902-----------------------------
INT 2F - WHOA!.COM - SET DELAY COUNT
AX = 8902h
BX = delay count (larger values slow system down more)
Return: AL = FDh successful
= FEh error
Note: WHOA!.COM is a system slow-down utility by Brad D Crandall
SeeAlso: AX=8900h
----------2F9000-----------------------------
INT 2F U - RAID - INSTALLATION CHECK
AX = 9000h
Return: AL = FFh if installed
Note: RAID (Resident AID) is a TSR utility program by Ross Neilson Wentworth
that resides mostly in EMS
----------2F9001-----------------------------
INT 2F U - RAID - GET ???
AX = 9001h
Return: DX:AX -> ???
SeeAlso: AX=9000h
----------2F9002-----------------------------
INT 2F U - RAID - GET RESIDENT SEGMENT
AX = 9002h
Return: AX = segment of resident (conventional memory) portion
SeeAlso: AX=9000h
----------2F9003-----------------------------
INT 2F U - RAID - UNINSTALL
AX = 9003h
Return: ???
SeeAlso: AX=9000h
----------2F9004-----------------------------
INT 2F U - RAID - GET ???
AX = 9004h
Return: AX = first available paragraph past end of resident portion???
CX destroyed
SeeAlso: AX=9000h
----------2F92-------------------------------
INT 2F - Couriers LAN E-Mail - API
AH = 92h
AL = function
00h installation check
01h uninstall
02h pop down MICRO.EXE notification window
03h ???
04h ???
05h ???
Return: ???
SeeAlso: AH=9Ch
----------2F93-------------------------------
INT 2F - InnerMission v1.7+ - INSTALLATION CHECK
AH = 93h
BX = CX = AX
Return: AL = FFh if installed and BX=CX=AX on entry
BX = segment of resident code
= 01h if installed but BX or CX differ from AX
Note: InnerMission is a shareware graphical screen blanker by Kevin Stokes
----------2F9C-------------------------------
INT 2F - Couriers LAN E-Mail OPERATOR.EXE - API
AH = 9Ch
AL = subfunction
01h uninstall
Return: ???
SeeAlso: AH=92h
----------2FA1--BX0081-----------------------
INT 2F - Ergo DOS extenders - INSTALLATION CHECK
AH = A1h
BX = 0081h
AL = which
FEh OS/286,OS/386
FFh HummingBoard DOS extender
ES:DI -> 16-byte buffer
Return: if installed, first four bytes of ES:DI buffer are "IABH"
Note: since TKERNEL is a licensed version, it is likely that subfunctions
BX=0082h and BX=0084h are present and function identically to the
AX=FBA1h/BX=008xh calls
SeeAlso: AX=ED00h,AX=FBA1h,INT 15/AX=BF02h
----------2FA189-----------------------------
INT 2F U - Biologic HRAMDEV.SYS - API
AX = A189h
BX = subfunction
0000h set ???
0001h remove ???
0002h get status ???
0003h enable ???
0004h disable ???
0005h set ??? flag
0006h clear ??? flag
0007h set ??? flag
0008h clear ??? flag
0009h set ???
ES:DI -> function-specific arguments
if func 0000h: 20-byte buffer containing ???
if func 0001h: 20-byte buffer for returned ???
if func 0002h: 16-byte buffer for returned ???
if func 0009h: WORD containing ???
Return: BX = A189h if installed
AH = status
00h successful
FFh failed or invalid function number
Notes: HRAMDEV.SYS is a part of the shareware package HRAM by Biologic which
provides improved high memory access under MSDOS 5.0
functions 00h and 01h use a stack of four entries; function 01h always
removes the values stored with the most recent function 00h call
which has not yet been matched with a function 01h call.
----------2FA4E0-----------------------------
INT 2F - Futurus Team - INSTALLATION CHECK
AX = A4E0h
Return: AL = 52h ("R") if installed
AH = major version plus 30h ("0")
ES:BX -> ??? (INT A4 handler???)
Note: older versions of Right Hand Man (from which Team evolved) store the
signature "RH" at offset 103h in the INT 2F handler's segment
SeeAlso: INT A4"Right Hand Man"
----------2FA900-----------------------------
INT 2F - METZTSR.COM - INSTALLATION CHECK
AX = A900h
CF set
Return: CF clear if resident
AX = 97FFh
CF set if not present
Notes: METZTSR.COM prevents METZ applications (such as the MAGIC screen
saver) inactivity timeout while running a DOSapp under MS Windows.
the default multiplex number is A9h, but may be set to any value from
80h to FFh with a commandline switch
SeeAlso: AX=A901h,AX=A902h
----------2FA901-----------------------------
INT 2F - METZTSR.COM - GET TIME OF LAST KEYBOARD ACTIVITY
AX = A901h
CF set
Return: CF clear if successful
AX:DX = BIOS time at which INT 09 was last invoked
CF set if not present
SeeAlso: INT 09,INT 1A/AH=00h
----------2FA902-----------------------------
INT 2F - METZTSR.COM - SET METZ Ctrl-Alt-Del FLAG
AX = A902h
BL = new value
00h Ctrl-Alt-Del not allowed
else Ctrl-Alt-Del allowed (startup default is 01h)
CF set
Return: CF clear if successful
AX = 97FFh
CF set if not resident
SeeAlso: AX=A903h
----------2FA903-----------------------------
INT 2F - METZTSR.COM - GET METZ Ctrl-Alt-Del FLAG
AX = A903h
CF set
Return: CF clear if successful
AX = 97FFh if Ctrl-Alt-Del allowed
AX = 0000h if Ctrl-Alt-Del not allowed
CF set if not resident
SeeAlso: AX=A902h
----------2FAA00-----------------------------
INT 2F - VIDCLOCK.COM - INSTALLATION CHECK
AX = AA00h
Return: AL = 00h not installed
FFh installed
Note: VIDCLOCK.COM is a memory-resident clock by Thomas G. Hanlin III
----------2FAB00-----------------------------
INT 2F - Btrieve Multi-User - INSTALLATION CHECK
AX = AB00h
Return: AL = 4Dh if installed
SeeAlso: AX=AB01h,AX=AB02h,INT 21/AX=3000h"Btrieve",INT 7B"Btrieve"
----------2FAB01-----------------------------
INT 2F - Btrieve Multi-User - EXECUTE Btrieve OPERATION
AX = AB01h
BX = process ID
DS:DX -> 38-byte parameter record (see INT 7B"Btrieve")
Return: AL = 00h OK
= other retry after calling INT 7F/AX=0200h
SeeAlso: AX=AB00h,AX=AB02h,INT 7B"Btrieve",INT 7F/AX=0200h
----------2FAB02-----------------------------
INT 2F - Btrieve Multi-User - GET NEW PROCESS ID
AX = AB02h
Return: AL = 00h succesful
BX = process ID
AL > 00h failed, retry after calling INT 7F/AX=0200h
SeeAlso: AX=AB00h,AX=AB01h,INT 7B"Btrieve",INT 7F/AX=0200h
----------2FAC00-----------------------------
INT 2F - DOS 4.01+ GRAPHICS.COM - INSTALLATION CHECK
AX = AC00h
Return: AX = FFFFh
ES:DI -> ??? (graphics data?) (not documented)
Note: this installation check was moved here to avoid the conflict with the
CD-ROM extensions that occurred in DOS 4.00
SeeAlso: AX=1500h"GRAPHICS"
----------2FAD00-----------------------------
INT 2F U - DOS 3.3+ DISPLAY.SYS internal - INSTALLATION CHECK
AX = AD00h
Return: AL = FFh if installed
BX = ??? (0100h in MS-DOS 3.30, PCDOS 4.01)
Note: DOS 5.0 DISPLAY.SYS chains to previous handler if AL is not one of the
subfunctions listed here
----------2FAD01-----------------------------
INT 2F U - DOS 3.3+ DISPLAY.SYS internal - SET ACTIVE CODE PAGE
AX = AD01h
BX = new code page
Return: CF clear if successful
AX = 0001h
CF set on error (unsupported code page)
AX = 0000h
SeeAlso: AX=AD02h
----------2FAD02-----------------------------
INT 2F U - DOS 3.3+ DISPLAY.SYS internal - GET ACTIVE CODE PAGE
AX = AD02h
Return: CF set if code page never set
AX = 0001h
BX = FFFFh (assume first hardware code page)
CF clear if successful
BX = current code page
SeeAlso: AX=AD01h,AX=AD03h
----------2FAD03-----------------------------
INT 2F U - DOS 3.3+ DISPLAY.SYS internal - GET CODE PAGE INFORMATION
AX = AD03h
ES:DI -> buffer for code page information (see below)
CX = size of buffer in bytes
Return: CF set if buffer too small
CF clear if successful
ES:DI buffer filled
SeeAlso: AX=AD01h,AX=AD02h

Format of DOS 5.0 code page information:
Offset Size Description
00h WORD number of software code pages
02h WORD ??? (0003h)
04h WORD number of hardware code pages
06h N WORDs hardware code page numbers
N WORDs software (prepared) code pages (FFFFh if not yet prepared)
----------2FAD04-----------------------------
INT 2F U - DOS 4.x only DISPLAY.SYS internal - ???
AX = AD04h
???
Return: ???
----------2FAD10-----------------------------
INT 2F U - DOS 4.x DISPLAY.SYS internal - INSTALLATION CHECK???
AX = AD10h
???
Return: AX = FFFFh
BX = ??? (0100h in PCDOS 4.01)
----------2FAD10-----------------------------
INT 2F U - DOS 5.0 DISPLAY.SYS internal - ???
AX = AD10h
???
Return: CF clear if successful
CF set on error
Note: this function is a NOP if the active code page has never been set
(AX=AD02h returns BX=FFFFh); its purpose otherwise is not known
----------2FAD40-----------------------------
INT 2F - DOS 4.0 - ???
AX = AD40h
DX = ???
???
Return: ???
Note: called by PCDOS 4.01 PRINT.COM
----------2FAD80-----------------------------
INT 2F u - DOS 3.3+ KEYB.COM internal - INSTALLATION CHECK
AX = AD80h
Return: AL = FFh if installed
BX = version number (BH = major, BL = minor)
ES:DI -> internal data (see below)
Notes: MSDOS 3.30, PCDOS 4.01, and MSDOS 5.00 all report version 1.00.
undocumented prior to the release of DOS 5.0

Format of KEYB internal data:
Offset Size Description
00h DWORD original INT 09
04h DWORD original INT 2F
08h 6 BYTEs ???
0Eh WORD flags
10h BYTE ???
11h BYTE ???
12h 4 BYTEs ???
16h 2 BYTEs country ID letters
18h WORD current code page
---DOS 3.3---
1Ah WORD pointer to first item in list of code page tables???
1Ch WORD pointer to ??? item in list of code page tables
1Eh 2 BYTEs ???
20h WORD pointer to key translation data
22h WORD pointer to last item in code page table list (see below)
24h 9 BYTEs ???
---DOS 4.01---
1Ah 2 BYTEs ???
1Ch WORD pointer to first item in list of code page tables???
1Eh WORD pointer to ??? item in list of code page tables
20h 2 BYTEs ???
22h WORD pointer to key translation data
24h WORD pointer to last item in code page table list (see below)
26h 9 BYTEs ???

Format of code page table list entries:
Offset Size Description
00h WORD pointer to next item, FFFFh = last
02h WORD code page
04h 2 BYTEs ???

Format of translation data:
Offset Size Description
00h WORD size of data in bytes, including this word
02h N-2 BYTEs ???
----------2FAD81-----------------------------
INT 2F - DOS 3.3+ KEYB.COM - SET KEYBOARD CODE PAGE
AX = AD81h
BX = code page (see INT 21/AX=6601h)
Return: CF set on error
AX = 0001h (code page not available)
CF clear if successful
Notes: called by DISPLAY.SYS
undocumented prior to the release of DOS 5.0
SeeAlso: AX=AD82h
----------2FAD82-----------------------------
INT 2F - DOS 3.3+ KEYB.COM - SET KEYBOARD MAPPING
AX = AD82h
BL = new state
00h US keyboard (Control-Alt-F1)
FFh foreign keyboard (Control-Alt-F2)
Return: CF set on error (BL not 00h or FFh)
CF clear if successful
Note: undocumented prior to the release of DOS 5.0
SeeAlso: AX=AD81h,AX=AD83h
----------2FAD83-----------------------------
INT 2F - DOS 5.0 KEYB.COM - GET KEYBOARD MAPPING
AX = AD83h
Return: BL = current state
00h US keyboard
FFh foreign keyboard
SeeAlso: AX=AD82h
----------2FAE00DXFFFF-----------------------
INT 2F U - DOS 3.3+ internal - INSTALLABLE COMMAND - INSTALLATION CHECK
AX = AE00h
DX = FFFFh
CH = FFh
CL = length of command line tail (4DOS v4.0)
DS:BX -> command line buffer (see below)
DS:SI -> command name buffer (see below)
DI = 0000h (4DOS v4.0)
Return: AL = FFh if this command is a TSR extension to COMMAND.COM
AL = 00h if the command should be executed as usual
Notes: This call provides a mechanism for TSRs to install permanent
extensions to the command repertoire of COMMAND.COM. It appears
that COMMAND.COM makes this call before executing the current
command line, and does not execute it itself if the return is FFh.
APPEND hooks this call, to allow subsequent APPEND commands to
execute without re-running APPEND

Format of command line buffer:
Offset Size Description
00h BYTE max length of command line, as in INT 21/AH=0Ah
01h BYTE count of bytes to follow, excluding terminating 0Dh
N BYTEs command line text, terminated by 0Dh

Format of command name buffer:
Offset Size Description
00h BYTE length of command name
01h N BYTEs uppercased command name (blank-padded to 11 chars by 4DOS v4)
----------2FAE01DXFFFF-----------------------
INT 2F U - DOS 3.3+ internal - INSTALLABLE COMMAND - EXECUTE
AX = AE01h
DX = FFFFh
CH = 00h
CL = length of command name (4DOS v4.0)
DS:SI -> command name buffer (see AX=AE00h)
DS:BX -> command line buffer (see AX=AE00h)
Return: DS:SI buffer updated
if length byte is nonzero, the following bytes contain the uppercase
internal command to execute and the command line buffer contains the
command's parameters (the first DS:[SI] bytes are ignored)
Notes: this call requests execution of the command which a previous call to
AX=AE00h indicated was resident
APPEND hooks this call
----------2FB000-----------------------------
INT 2F - DOS 3.3+ GRAFTABL.COM - INSTALLATION CHECK
AX = B000h
Return: AL = 00h not installed, OK to install
= 01h not installed, not OK to install
= FFh installed
Notes: called by DISPLAY.SYS
documented for DOS 5.0, but undocumented in prior versions
SeeAlso: AX=B001h
----------2FB001-----------------------------
INT 2F - DOS 3.3+ GRAFTABL.COM - GET GRAPHICS FONT TABLE
AX = B001h
DS:BX -> DWORD buffer for address of 8x8 font table
Return: buffer filled
AL = FFh
Note: PCDOS 3.30/4.01 set the font table offset to 0130h, MSDOS 3.30 to 0030h
SeeAlso: AX=B000h
----------2FB400-----------------------------
INT 2F - IBM PC3270 EMULATION PROG v3 - INSTALLATION CHECK
AX = B400h
Return: AL = FFh if installed
----------2FB401-----------------------------
INT 2F - IBM PC3270 EMULATION PROG v3 - GET HOST BUFFER ADDRESS
AX = B401h
Return: ES -> host screen buffer (PC ASCII format)
ES unchanged if communications not started
----------2FB402-----------------------------
INT 2F - IBM PC3270 EMULATION PROG v3 - ???
AX = B402h
BX = ???
Return: ???
----------2FB403-----------------------------
INT 2F - IBM PC3270 EMULATION PROG v3 - ???
AX = B403h
???
Return: ???
----------2FB404-----------------------------
INT 2F - IBM PC3270 EMULATION PROG v3 - ???
AX = B404h
???
Return: ???
----------2FB405-----------------------------
INT 2F - IBM PC3270 EMULATION PROG v3 - ???
AX = B405h
???
Return: ???
----------2FB700-----------------------------
INT 2F - APPEND - INSTALLATION CHECK
AX = B700h
Return: AL = status
00h not installed
FFh installed
Note: MSDOS 3.30 APPEND refuses to install itself when run inside TopView or
a TopView-compatible environment
----------2FB701-----------------------------
INT 2F U - APPEND - ???
AX = B701h
???
Return: ???
Note: MSDOS 3.30 APPEND displays "Incorrect APPEND Version" and aborts caller
----------2FB702-----------------------------
INT 2F - APPEND - VERSION CHECK
AX = B702h
Return: AX = FFFFh if not DOS 4.0 APPEND (also if DOS 5.0 APPEND)
AL = major version number
AH = minor version number, otherwise
SeeAlso: AX=B710h
----------2FB703-----------------------------
INT 2F U - DOS 3.3, DOS 5.0 APPEND - HOOK INT 21
AX = B703h
ES:DI -> INT 21 handler APPEND should chain to
Return: ES:DI -> APPEND's INT 21 handler
Note: each invocation of this function toggles a flag which APPEND uses to
determine whether to chain to the user handler or the original
INT 21
----------2FB704-----------------------------
INT 2F - DOS 3.3+ APPEND - GET APPEND PATH
AX = B704h
Return: ES:DI -> active APPEND path (128 bytes max)
----------2FB706-----------------------------
INT 2F - DOS 4+ APPEND - GET APPEND FUNCTION STATE
AX = B706h
Return: BX = APPEND state
bit 0: set if APPEND enabled
bits 1-11 reserved
bit 12: (DOS 5.0) set if APPEND applies directory search even if a
drive has been specified
bit 13: set if /PATH flag active
bit 14: set if /E flag active (environment var APPEND exists)
bit 15: set if /X flag active
----------2FB707-----------------------------
INT 2F - DOS 4+ APPEND - SET APPEND FUNCTION STATE
AX = B707h
BX = APPEND state bits (see AX=B706h)
----------2FB710-----------------------------
INT 2F U - DOS 3.3+ APPEND - GET VERSION INFO
AX = B710h
Return: AX = current APPEND state (see AX=B706h)
BX = ??? (0000h in MSDOS 3.30 and 5.00)
CX = ??? (0000h in MSDOS 3.30 and 5.00)
DL = major version
DH = minor version
SeeAlso: AX=B702h
----------2FB711-----------------------------
INT 2F - DOS 4+ APPEND - SET RETURN FOUND NAME STATE
AX = B711h
Note: if the next INT 21h call (and ONLY the next) is function 3Dh, 43h, or
6Ch (also 4B03h and 4Eh if /X active), the fully qualified filename is
written over top of the filename passed to the INT 21h call. The
application must provide a sufficiently large buffer. This state is
reset after the next INT 21h call processed by APPEND.
BUG: DOS 4.0 APPEND reportedly overwrites DS:DX instead of DS:SI for
INT 21/AH=6Ch
SeeAlso: INT 21/AH=4Eh
----------2FB800-----------------------------
INT 2F - network - INSTALLATION CHECK
AX = B800h
Return: AL = status
00h not installed
nonzero installed
BX = installed component flags (test in this order!)
bit 6 server
bit 2 messenger
bit 7 receiver
bit 3 redirector
----------2FB803-----------------------------
INT 2F - network - GET NETWORK EVENT POST HANDLER
AX = B803h
Return: ES:BX -> event post handler (see AX=B804h)
SeeAlso: AX=B804h,AX=B903h
----------2FB804-----------------------------
INT 2F - network - SET NETWORK EVENT POST HANDLER
AX = B804h
ES:BX -> new event post handler
Notes: used in conjunction with AX=B803h to hook into the network event post
routine
The specified handler is called on any network event. Two events are
defined: message received and critical network error.
SeeAlso: AX=B803h,AX=B904h

Values post routine is called with:
AX = 0000h single block message
DS:SI -> ASCIZ originator name
DS:DI -> ASCIZ destination name
ES:BX -> text header (see below)
AX = 0001h start multiple message block
CX = block group ID
DS:SI -> ASCIZ originator name
DS:DI -> ASCIZ destination name
AX = 0002h multiple block text
CX = block group ID
ES:BX -> text header (see below)
AX = 0003h end multiple block message
CX = block group ID
AX = 0004h message aborted due to error
CX = block group ID
AX = 0101h server received badly formatted network request
Return: AX = FFFFh (PC LAN will process error)
AX = 0102h unexpected network error
ES:BX -> NCB (see INT 5C)
AX = 0103h server received INT 24 error
other registers as for INT 24, except AH is in BH
Return: as below, but only 0000h and FFFFh allowed
Return: AX = response code
0000h user post routine processed message
0001h PC LAN will process message, but message window not displayed
FFFFh PC LAN will process message

Format of text header:
Offset Size Description
00h WORD length of text (maximum 512 bytes)
02h N BYTEs text of message
Note: all CRLF sequences in message text are replaced by 14h
----------2FB807-----------------------------
INT 2F - Network - GET NetBIOS NAME NUMBER OF MACHINE NAME
AX = B807h
Return: CH = NetBIOS name number of the machine name
SeeAlso: INT 21/AX=5E00h
----------2FB808-----------------------------
INT 2F U - Network - RELINK KEYBOARD HANDLER
AX = B808h
ES:BX -> INT 09 handler network should call after it finishes INT 09
Notes: this call replaces the address to which the network software chains on
an INT 09 without preserving the original value. This allows a prior
handler to unlink, but does not allow a new handler to be added
such that the network gets the INT 09 first unless the new handler
completely takes over INT 09 and never chains.
called by DOS 3.2 KEYBxx.COM
SeeAlso: AX=B908h
----------2FB809-----------------------------
INT 2F - LANtastic Network, NetWare Lite - VERSION CHECK
AX = B809h
Return: AH = major version
AL = minor version (decimal)
----------2FB900-----------------------------
INT 2F - PC Network RECEIVER.COM - INSTALLATION CHECK
AX = B900h
Return: AL = 00h if not installed
FFh if installed
----------2FB901-----------------------------
INT 2F - PC Network RECEIVER.COM - GET RECEIVER.COM INT 2F HANDLER ADDRESS
AX = B901h
Return: AL = ???
ES:BX -> RECEIVER.COM INT 2F handler
Note: allows more efficient execution by letting the caller bypass any other
INT 2F handlers which have been added since RECEIVER.COM was
installed
----------2FB903-----------------------------
INT 2F - PC Network RECEIVER.COM - GET RECEIVER.COM POST ADDRESS
AX = B903h
Return: ES:BX -> POST handler
SeeAlso: AX=B803h,AX=B904h
----------2FB904-----------------------------
INT 2F - PC Network RECEIVER.COM - SET RECEIVER.COM POST ADDRESS
AX = B904h
ES:BX -> new POST handler
SeeAlso: AX=B804h,AX=B903h
----------2FB905-----------------------------
INT 2F - PC Network RECEIVER.COM - GET FILENAME
AX = B905h
DS:BX -> 128-byte buffer for filename 1
DS:DX -> 128-byte buffer for filename 2
Return: buffers filled from RECEIVER.COM internal buffers
Note: use of filenames is unknown, but one appears to be for storing messages
SeeAlso: AX=B906h
----------2FB906-----------------------------
INT 2F - PC Network RECEIVER.COM - SET FILENAME
AX = B906h
DS:BX -> 128-byte buffer for filename 1
DS:DX -> 128-byte buffer for filename 2
Return: RECEIVER.COM internal buffers filled from user buffers
Note: use of filenames is unknown, but one appears to be for storing messages
SeeAlso: AX=B905h
----------2FB908-----------------------------
INT 2F - PC Network RECEIVER.COM - UNLINK KEYBOARD HANDLER
AX = B908h
ES:BX -> INT 09 handler RECEIVER should call after it finishes INT 09
Note: this call replaces the address to which RECEIVER.COM chains on an
INT 09 without preserving the original value. This allows a prior
handler to unlink, but does not allow a new handler to be added
such that RECEIVER gets the INT 09 first.
SeeAlso: AX=B808h
----------2FBC00-----------------------------
INT 2F - Windows 3.0, DOS 5.0 EGA.SYS - INSTALLATION CHECK
AX = BC00h
Return: AL = 00h not installed, OK to install
= 01h not installed, not OK to install
= FFh installed
BX = 5456h ("TV")
Note: AH=BCh is the default value, which may be changed by a command line
parameter to any value between 80h and FFh
SeeAlso: AX=BC06h,INT 10/AH=FAh"EGA"
----------2FBC06-----------------------------
INT 2F U - MS Windows 3.0, DOS 5.0 EGA.SYS - GET VERSION INFO
AX = BC06h
Return: BX = 5456h ("TV")
CH = major version
CL = minor version
DL = revision
SeeAlso: AX=BC00h,INT 10/AH=FAh"EGA"
----------2FBE00-----------------------------
INT 2F - REDVIEW - INSTALLATION CHECK
AX = BE00h
Return: AL = FFh if installed
Note: REDVIEW is a public-domain TSR by Alexandr Novy and Petr Horak which
copies data sent to standard output to standard error when the
former has been redirected to a file, thus allowing the data to
be seen on the screen at the same time it is captured in a file
----------2FBF00-----------------------------
INT 2F - PC LAN PROGRAM REDIRIFS.EXE internal - INSTALLATION CHECK
AX = BF00h
Return: AL = FFh if installed
----------2FBF01-----------------------------
INT 2F U - PC LAN PROGRAM REDIRIFS.EXE internal - ???
AX = BF01h
???
Return: ???
----------2FBF80-----------------------------
INT 2F - PC LAN PROG REDIR.SYS internal - SET REDIRIFS ENTRY POINT
AX = BF80h
ES:DI -> FAR entry point to IFS handler in REDIRIFS
Return: AL = FFh if installed
ES:DI -> internal workspace
Note: all future IFS calls to REDIR.SYS are passed to the ES:DI entry point
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