TITLE 'MEX RACAL-VADIC MAXWELL 1200V OVERLAY V1.0'
;
; (DELETE ABOVE TITLE LINE IF ASSEMBLING WITH ASM)
;
; MXO-MW10.ASM
;. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
; Revised from and thanks to: .
; .
; MXO-RV10.ASM Original release 5/20/84 .
; .
; Racal Vadic VA212 overlay for MEX: revision 1.2 .
; Written 20 May 1984 by Dave Mabry .
; Adapted using information and excerpts from Ron Fowler's .
; overlay for the PMMI modem. .
;. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . .
;
; MXO-MW10.ASM Released 9/25/84
; Racal-Vadic Maxwell 1200V overlay for mex revision 1.0
; questions or comments; leave message on Dark Chambers RiBBs
; (206)481-6549
; Jim van der Heyden
;
; This overlay will work with any modem overlay that terminates
; prior to 0B00H
;
FALSE EQU 0
TRUE EQU NOT FALSE
;
;
; SYSTEM CONSTANTS
;
DIALV EQU 0162H ;LOCATION OF DIAL VECTOR IN OVERLAY
DISCV EQU 0165H ;LOCATION OF DISCONNECT VECTOR IN OVERLAY
DIALOC EQU 0B00H ;DIALING CODE GOES HERE
;
;
; MEX service processor stuff ... MEX supports an overlay service
; processor, located at 0D00H (and maintained at this address from
; version to version). If your overlay needs to call BDOS for any
; reason, it should call MEX instead; function calls below about
; 240 are simply passed on to the BDOS (console and list I/O calls
; are specially handled to allow modem port queueing, which is why
; you should call MEX instead of BDOS). MEX uses function calls
; above about 244 for special overlay services (described below).
;
; Some sophisticated overlays may need to do file I/O; if so, use
; the PARSFN MEX call with a pointer to the FCB in DE to parse out
; the name. This FCB should support a spare byte immediately pre-
; ceeding the actual FCB (to contain user # information). If you've
; used MEX-10 for input instead of BDOS-10 (or you're parsing part
; of a SET command line that's already been input), then MEX will
; take care of DU specs, and set up the FCB accordingly. There-
; after all file I/O calls done through the MEX service processor
; will handle drive and user with no further effort necessary on
; the part of the programmer.
;
MEX EQU 0D00H ;address of the service processor
INMDM EQU 255 ;get char from port to A, CY=no more in 100 ms
TIMER EQU 254 ;delay 100ms * reg B
TMDINP EQU 253 ;B=# secs to wait for char, cy=no char
CHEKCC EQU 252 ;check for ^C from KBD, Z=present
SNDRDY EQU 251 ;test for modem-send ready
RCVRDY EQU 250 ;test for modem-receive ready
SNDCHR EQU 249 ;send a character to the modem (after sndrdy)
RCVCHR EQU 248 ;recv a char from modem (after rcvrdy)
LOOKUP EQU 247 ;table search: see CMDTBL comments for info
PARSFN EQU 246 ;parse filename from input stream
BDPARS EQU 245 ;parse baud-rate from input stream
SBLANK EQU 244 ;scan input stream to next non-blank
EVALA EQU 243 ;evaluate numeric from input stream
LKAHED EQU 242 ;get nxt char w/o removing from input
GNC EQU 241 ;get char from input, cy=1 if none
ILP EQU 240 ;inline print
DECOUT EQU 239 ;decimal output
PRBAUD EQU 238 ;print baud rate
;
;
CONOUT EQU 2 ;simulated BDOS function 2: console char out
PRINT EQU 9 ;simulated BDOS function 9: print string
INBUF EQU 10 ;input buffer, same structure as BDOS 10
;
;
CR EQU 13
LF EQU 10
;
;
ORG DIALV ;OVERLAY THE DIALING VECTOR
JMP DIAL
;
ORG DISCV
JMP DISCIT ;DISCONNECT VECTOR
;
;
; This is the DIAL routine called by MEX to dial a digit. The digit
; to be dialed is passed in the A register. Note that two special
; codes must be intercepted as non-digits: 254 (start dial sequence)
; and 255 (end-dial sequence). Mex will always call DIAL with 254
; in the accumulator prior to dialing a number. Mex will also call
; dial with 255 in A as an indication that dialing is complete. Thus,
; the overlay may use these values to "block" the number, holding it
; in a buffer until it is completely assembled (in fact, that's the
; scheme employed here for the Racal Vadic).
;
; After the 254-start-dial sequence, MEX will call the overlay with
; digits, one-at-a-time. MEX will make no assumptions about the dig-
; its, and will send each to the DIAL routine un-inspected (some modems,
; like the Smartmodem, allow special non-numeric characters in the
; phone number, and MEX may make no assumptions about these).
;
; After receiving the end-dial sequence (255) the overlay must take
; whatever end-of-dial actions are necessary *including* waiting for
; carrier at the distant end. The overlay should monitor the keyboard
; during this wait (using the MEX keystat service call), and return
; an exit code to MEX in the A register, as follows:
;
; 0 - Carrier detected, connection established
; 1 - Far end busy (only for modems that can detect this condition)
; 2 - No answer (or timed out waiting for modem response)
; 3 - Keyboard abort (^C only: all others should be ignored)
; 4 - Error reported by modem
;
; <No other codes should be returned after an end-dial sequence>
;
; The overlay should not loop forever in the carrier-wait routine, but
; instead use either the overlay timer vector, or the INMDMV (timed 100
; ms character wait) service call routine.
;
; The DIAL routine is free to use any of the registers, but must return
; the above code after an end-dial sequence
;
ORG DIALOC
;
DIAL: LHLD DIALPT ;FETCH POINTER
CPI 254 ;START DIAL?
JZ STDIAL ;JUMP IF SO
CPI 255 ;END DIAL?
JZ ENDIAL ;JUMP IF SO
;
; Not start or end sequence, must be a digit to be sent to the modem
;
MOV M,A ;PUT CHAR IN BUFFER
INX H ;ADVANCE POINTER
SHLD DIALPT ;STUFF PNTR
RET ;ALL DONE
;
; Here on a start-dial sequence
;
STDIAL: LXI H,DIALBF ;SET UP BUFFER POINTER
SHLD DIALPT
RET
;
; Here on an end-dial sequence
;
ENDIAL:
MVI M,0 ; Terminate phone number string
CLEAR:
MVI C,INMDM ; Clean out the data buffer in usart
CALL MEX
JNC CLEAR ; Get all available
CALL IDLE ; idle b-4 wakeup
LXI H,WAKEUP ; Get modem's attention
CALL RVSEND ; Send ^E,<cr>
CALL LFWAIT ; First thing after ^E,<cr>
RNZ ; Return if time out
CALL LFWAIT ; After "HELLO..."
RNZ ; Return if time out
LXI H,DCMD ; Send "dial" command to modem
CALL RVSEND
LXI H,DIALBF ; Point to number
CALL RVSEND ; Send it to modem
CALL SENDCR ; Send <cr> to terminate phone number
RNZ
;
; Here starts the main loop waiting for messages from the modem
; and interpreting them. Some are just passed to the console
; and others trigger a specific action.
;
DLOOP:
LXI H,RESPBF ; Point to response buffer
MVI C,255 ; Long wait here
CALL CATCHR ; Catch response from modem
ORA A ; Zero return code ?
JNZ IDLE ; No, disconnect and return error code
MOV A,B ; Get character count from CATCHR
ORA A ; Hope it isn't zero
JZ DLOOP ; If it is, then ignore this response
LXI H,RESPBF ; Point to string from modem
LXI D,RSPTBL ; Point to valid response table
CALL COMPR ; Find out which response we got
MOV A,B ; Get return value
CPI 255 ; No response match
JNZ DIAL05
NOANS:
CALL IDLE
MVI A,2 ;Tell MEX:no answer
RET
ERRET:
MVI A,4 ; Error return to MEX
JMP IDLE ; Disconnect and return error code
DIAL05:
CPI 3 ; Failed call? probally no answer!
JZ NOANS ; Error return
CPI 1 ; Dialing message ?
JNZ DIAL10
MVI C,ILP
CALL MEX
DB 'Dial..',0
JMP DLOOP
DIAL10:
CPI 2 ; Ringing ?
JNZ DIAL15
MVI C,ILP
CALL MEX
DB 'Ring..',0
JMP DLOOP
DIAL15:
CPI 4 ; Answer tone ?
JNZ DIAL20
MVI C,ILP
CALL MEX
DB 'Carrier..',0
JMP DLOOP
DIAL20:
CPI 5 ; On line ?
JNZ DIAL25
XRA A ; Return on line code to MEX
RET
DIAL25:
CPI 7 ; Busy ?
JNZ DIAL35
DIAL30:
MVI A,1 ; Return busy code to MEX
JMP IDLE ; Disconnect and return error code
DIAL35:
CPI 6 ; No dial tone?
JNZ DIAL40
PUSH B
PUSH D
PUSH H
MVI C,ILP
CALL MEX
DB 'No dial tone..',cr,lf,0
JMP UABORT
DIAL40:
CPI 8 ; Voice ?
JNZ ERRET ; If there was a match not handled above
;
; Handle "VOICE" here
;
CALL SENDCR ; <cr> ends the "voice" mode
JMP DIAL30 ; Abort and return busy code to MEX
;
; Disconnect vector is to disconnect modem from phone line
; whenever the ^J,N or when DSC is used.
;
DISCIT:
LXI H,QUITIT
CALL RVSEND
IDLE:
;
; Forces modem into idle state by sending "idle" command and
; then toggling DTR using the user's DISCV entry.
; Preserves any return code that may be in register A.
;
PUSH PSW ; Preserve any return code
CALL SENDCR ; Abort any dialing taking place
LXI H,IDLCMD ; Send idle message to modem
CALL RVSEND ; idle command modifed to 'I'
MVI C,TIMER ; Let's slow things down a bit
MVI B,1 ; 1/10 second.
CALL MEX
POP PSW ; Retrieve return code
RET
SENDCR:
;
; Sends a carriage return character to the modem and waits for a
; line feed character to be returned.
;
LXI H,CRMSG ; Send <cr> to modem
CALL RVSEND
; Note: execution falls through to LFWAIT
;
; Waits til the character from the modem is a line feed
; Returns the same codes as CATCHR.
;
LFWAIT:
MVI C,1 ; Up to one-Tenth second for <lf>
LXI H,RESPBF
JMP CATCHR ; Use CATCHR to wait for <lf>
; Table of valid responses from modem
RSPTBL:
DB 'HE',0 ; "hello..."
DB 'DI',0 ; "dialing..."
DB 'RI',0 ; "ringing..."
DB 'FA',0 ; "failed call"
DB 'AN',0 ; "answer tone"
DB 'ON',0 ; "on line"
DB 'NO',0 ; "no dial tone"
DB 'BU',0 ; "busy"
DB 'VO',0 ; "voice??"
DB 0 ; Table terminator
COMPR:
; Compares a string of characters in memory to a table of
; strings. Each entry of the table must be terminated by
; a zero byte, and the table must be terminated by another
; zero byte.
; Inputs: HL points to the string to look for
; DE points to the table
; Output: B contains the number of the table entry that
; matches the string, and a 255 if no entry matched.
;
MVI B,0 ; Init index
CMPR05:
MVI C,2 ; Number of characters to try to match
CMPR10:
LDAX D ; Fetch char from table
CMP M ; Same as char in string ?
JNZ CMPR15 ; Jump if not this entry in table
INX H ; Else, point to next char in string
INX D ; and next char in table entry
DCR C ; Decrement counter of characters
JNZ CMPR10 ; Go check next char
RET ; B contains the index of match
CMPR15:
INR B ; Increment index
CMPR20:
INX D ; Next char in table
LDAX D ; Get next char from table
ORA A ; Is it last char in that entry ?
JNZ CMPR20 ; No, keep looking
INX D ; Yes, then point to first char of next one
LDAX D ; Now check for end of table
ORA A ; Zero delimits table
JNZ CMPR05 ; Go check this table entry
MVI B,255 ; No match return code
RET
CATCHR:
;
; Catch response from modem.
; Input: HL pointing to buffer for characters from modem
; C delay allowed before timeout (multiples of 100ms)
; Output: Buffer contains the string received from modem with
; any control characters filtered out.
; C count of characters received before <cr>
; A error code: 0 ==> normal return
; 2 ==> time out occurred
; 3 ==> user typed ^C
;
MVI B,0 ; Character counter
CRLOOP:
MOV D,C ; Initialize count down timer
CRL05:
PUSH B ; Save character counter
PUSH D ; Save time out count down
PUSH H ; Save buffer pointer
MVI C,CHEKCC ; See if user typed ^C
CALL MEX
JZ UABORT ; If yes, jump to user abort code
MVI C,INMDM ; Else, continue
CALL MEX ; Get char in 1ms if available
POP H ; Restore working registers
POP D
POP B
JC NOCHAR ; If no char in 1ms, handle it
ANI 7FH ; Mask any parity bit
CPI LF ; End of line from modem ?
JZ EOL ; If <lf> then end of line
CPI ' ' ; Filter unwanted characters
JC CRLOOP ; Ignore control characters
CPI 'z'+1 ; Nothing above lower case alpha's
JNC CRLOOP
MOV M,A ; Here we have a valid character
INX H ; so save it and bump pointer
INR B ; Increment character counter also
JMP CRLOOP ; Go get the next one
;
; Handle no character from modem in 1ms
;
NOCHAR:
DCR D ; Decrement time out counter
JNZ CRL05 ; If not to zero, wait some more
MOV C,B ; Else, return with what we have now
MVI A,2 ; Time-out error code
RET
;
; End of line from modem
;
EOL:
MOV C,B ; Character count
XRA A ; Return zero
RET
;
; User abort from ^C
;
UABORT:
CALL IDLE ; Reset modem
POP H ; Since these are still on the stack
POP D
POP B
MOV C,B ; Count of characters up to now
MVI A,3 ; User abort code
RET
;
; Sends a string of characters pointed to by HL terminated by zero
;
RVSEND:
MVI C,SNDRDY ; Get modem send status
CALL MEX
JNZ RVSEND ; Wait for modem ready
MOV A,M ; Get character
INX H ; Point to next character
ORA A ; Is this the terminator ?
RZ ; If yes, done
MOV B,A ; Pass character in B
MVI C,SNDCHR ; Let MEX send to modem
CALL MEX
JMP RVSEND
;
; DATA AREA
;
WAKEUP: DB 'E'-40H,CR,0 ; String to wake up modem
IDLCMD: DB 'I',CR,0 ; Idle command
DCMD: DB 'D',0 ; Dial command to modem
CRMSG: DB CR,0 ; Note, this is end of DCMD
RESPBF: DS 20 ; Response from modem
DIALBF: DS 30 ; Phone number buffer
DIALPT: DS 2 ; Dial position pointer
QUITIT: DB 03,04,0 ; Disconnect modem codes
;
ENDm
;
EOL:
MOV C,B ; Character count
XRA A ; Return zero
RET
;
; User abort fro
