title 'MEX overlay for MEGA SuperComputer SBC'
;
; MXO-MG10.ASM -- MEX Overlay file for the MEGA SuperComputer SBC
;
; Version 1.0: Written 09/04/84 by Ron Fowler
;
; This overlay adapts the MEX modem program to the Mega Computer Co. Single
; Board Computer, using the Zilog SIO or DART.
;
; This overlay is adaptable to any computer using an SIO or DART for
; serial communications, and is especially useful if such adaptations
; are for computer with multiple SIO chips. It's also helpful if
; the target computer uses a CTC for generating the serial clock.
;
; This overlay is capable of setting baud rate and setting port number
; (via the SET command), and setting baud rate from the phone library.
;
; Note: to take advantage of software baud-rate selection, you must strap
; the MEGA baud-rate block (J10) as follows:
;
; CTCI0 - 19200\ For non-MEGA computers, this is a 307KB
; CTCI1 - 19200 > input clock rate (307KB/16=19200)
; CTCI2 - 19200/
; CTC00 - first SIO clock (RAn, RTAn/RTBn)--\
; CTC01 - second SIO clock --|
; CTC02 - third SIO clock --|
; |------/
; |
; These may be to any of the 6 SIO
; clock lines, but MAX of three unless
; you hack in another CTC. You must
; change the values in CTCTBL if you
; don't use CTC port 4 -- SIO on P5
; CTC port 5 -- SIO on P6
; CTC port 6 -- SIO on P3
;
; The SIO channels are numbered as follows:
;
; PORT Connector SIO Chip
; ---- --------- --------
; 0 P5 U61
; 1 P6 U61
; 2 P3 U58
; 3 P4 U58 (usually, the console)
; 4 P7 U64
; 5 P8 U64
;
; The reason for this strange numbering scheme is for compatibility with
; MEGA TurboDOS, where ports 4,5 don't exist (U64 is the network control-
; ler port for TurboDOS, and is not used for RS232 serial communications).
;
; Be aware that, if you're running MEGA TurboDOS, this overlay will dis-
; able the interrupts of any port it's SET to ... you can use the TurboDOS
; version of MEX if this is a problem. You might prefer to use this overlay
; to communicate in terminal mode at the higher baudrates, which is a losing
; situation with the TurboDOS MEX.
;
; Set the following NPORT value to the relative port # (table above) you
; want MEX to use on start up.
;
NPORT EQU 1
;
REV EQU 10 ;V 1.0
;
RDA EQU 1 ;mask for recv-data available
TBE EQU 4 ;mask for transmit-bufr empty
;
; MEX service processor stuff
;
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
;
PRINT EQU 9 ;BDOS/MEX print-string function call
;
BELL EQU 7 ;bell
TAB EQU 9
CR EQU 13 ;carriage return
LF EQU 10 ;linefeed
ESC EQU 1BH ;escape
YES EQU 0FFH
NO EQU 0
;
;
ORG 100H
;
; Change the clock speed to suit your system
;
DS 3 ;(for "JMP START" instruction)
DB NO ;yes=PMMI S-100 Modem 103H
DB NO ;yes=HAYES Smartmodem, no=non-PMMI 104H
DB 'T' ;T=touch, P=pulse (Smartmodem-only) 105H
CLOCK: DB 50 ;clock speed in MHz x10, 25.5 MHz max. 106H
;20=2 MHh, 37=3.68 MHz, 40=4 MHz, etc.
MSPEED: DB 5 ;0=110 1=300 2=450 3=600 4=710 5=1200 107H
;6=2400 7=4800 8=9600 9=19200 default
BYTDLY: DB 5 ;0=0 delay 1=10ms 5=50 ms - 9=90 ms 108H
;default time to send character in ter-
;minal mode file transfer for slow BBS.
CRDLY: DB 5 ;0=0 delay 1=100 ms 5=500 ms - 9=900 ms 109H
;default time for extra wait after CRLF
;in terminal mode file transfer
COLUMS: DB 5 ;number of DIR columns shown 10AH
SETFLG: DB YES ;yes=user-added Setup routine 10BH
SCRTST: DB YES ;Cursor control routine 10CH
DB YES ;yes=resend a record after any non-ACK 10DH
;no=resend a record after a valid-NAK
BAKFLG: DB YES ;yes=change any file same name to .BAK 10EH
CRCDFL: DB NO ;yes=default to CRC checking 10FH
TOGCRC: DB YES ;yes=allow toggling of CRC to Checksum 110H
CVTBS: DB NO ;yes=convert backspace to rub 111H
TOGLBK: DB YES ;yes=allow toggling of bksp to rub 112H
ADDLF: DB NO ;no=no LF after CR to send file in 113H
;terminal mode (added by remote echo)
TOGLF: DB YES ;yes=allow toggling of LF after CR 114H
DB YES ;yes=allow transmission of logon 115H
;write logon sequence at location LOGON
SAVCCP: DB YES ;yes=do not overwrite CCP 116H
DB NO ;yes=local command if EXTCHR precedes 117H
;no=external command if EXTCHR precedes
DB YES ;yes=allow toggling of LOCONEXTCHR 118H
LSTTST: DB YES ;yes=printer available on printer port 119H
XOFTST: DB NO ;yes=checks for XOFF from remote while 11AH
;sending a file in terminal mode
XONWT: DB NO ;yes=wait for XON after CR while 11BH
;sending a file in terminal mode
TOGXOF: DB YES ;yes=allow toggling of XOFF checking 11CH
IGNCTL: DB NO ;yes=CTL-chars above ^M not displayed 11DH
EXTRA1: DB 0 ;for future expansion 11EH
EXITCHR DB 'E'-40H ;^E = Exit to main menu 11FH
BRKCHR: DB '@'-40H ;^@ = Send 300 ms. break tone 120H
NOCONN: DB 'N'-40H ;^N = Disconnect from the phone line 121H
LOGCHR: DB 'L'-40H ;^L = Send logon 122H
LSTCHR: DB 'P'-40H ;^P = Toggle printer 123H
UNSAVE: DB 'R'-40H ;^R = Close input text buffer 124H
TRNCHR: DB 'T'-40H ;^T = Transmit file to remote 125H
SAVCHR: DB 'Y'-40H ;^Y = Open input text buffer 126H
EXTCHR: DB '^'-40H ;^^ = Send next character 127H
DS 2 ;unused by MEX 128H
;
INCTL1: JMP INSP ;go input status port 12AH
DS 7
;
OTDATA: JMP OUTDP ;go output data port 134H
DS 7
;
INPORT: JMP INDP ;go input data port 13EH
DS 7
;
MASKR: ANI RDA ! RET ;bit to test for receive ready 148H
TESTR: CPI RDA ! RET ;value of rcv. bit when ready 14BH
MASKS: ANI TBE ! RET ;bit to test for send ready 14EH
TESTS: CPI TBE ! RET ;value of send bit when ready 151H
DS 14 ; 156H
;
;
DS 3 ;DIALV: not done here (maybe MXO-SM) 162H
DISCV: JMP DISCON ;disconnect
GOODBV: JMP GOODBY ; 168H
INMODV: JMP NITMOD ;go to user written routine 16BH
RET ! NOP ! NOP ;NEWBDV 16EH
RET ! NOP ! NOP ;NOPARV 171H
RET ! NOP ! NOP ;PARITV 174H
SETUPV: JMP SETCMD ; 177H
DS 3 ;not used by MEX 17AH
VERSNV: JMP SYSVER ; 17DH
BREAKV: JMP SBREAK ; 180H
;
; Do not change the following six lines (they provide access to routines
; in MEX that are present to support MDM7 overlays -- they will likely
; be gone by MEX v2.0).
;
ILPRTV: DS 3 ; 183H
INBUFV DS 3 ; 186H
ILCMPV: DS 3 ; 189H
INMDMV: DS 3 ; 18CH
DS 3 ; 18FH
TIMERV DS 3 ; 192H
;
; Routine to clear to end of screen. If using CLREOS and CLRSCRN, set
; SCRTEST to YES at 010AH (above).
;
CLREOS: LXI D,EOSMSG ; 195H
MVI C,PRINT
CALL MEX
RET
;
CLS: LXI D,CLSMSG ; 19EH
MVI C,PRINT
CALL MEX
RET
; 1A7H
;
; end of fixed area
;
SYSVER: MVI C,ILP ;in-line print
CALL MEX
DB 'MEGA SuperComputer rev '
DB REV/10+'0'
DB '.'
DB REV MOD 10+'0'
DB CR,LF,0
RET
;
; Routine to exit just prior to exit-to-cpm
;
GOODBY: RET ;not done here
;
; Send break to remote
;
SBREAK: RET ;not yet implemented
;
; Disconnect the modem (not done here, relies on SM overlay)
;
DISCON: RET
;
; SET command: select baud rate, port name. Port name may be any of
; ABC, DELTA, USR (names may be changed by altering PNMTBL entries),
; baud rate any of xxxxxxxxxxxxxxxxxxxxx
; Special set-port syntax allows baud rate after port name. Examples:
;
; SET PORT DELTA3
; SET PORT ABC 1200
; SET PORT USR 300
; SET BAUD 9600
;
SETCMD: MVI C,SBLANK ;any arguments?
CALL MEX
JC TELL ;if not, go display port/baud
LXI D,CMDTBL
MVI C,LOOKUP
CALL MEX ;parse argument
PUSH H ;save any parsed argument adrs on stack
RNC ;if we have one, return to it
POP H ;oops, input not found in table
SETERR: MVI C,ILP ;inline print
CALL MEX
DB CR,LF,'SET command error',CR,LF,0
RET
;
; Argument table
;
CMDTBL: DB '?'+80H ;help
DW STHELP
DB 'BAU','D'+80H ;"set baud"
DW STBAUD
DB 'POR','T'+80H ;"set port"
DW SETPOR
DB 0 ;<<=== table terminator
;
; "SET ?" processor
;
STHELP: MVI C,ILP ;inline print
CALL MEX
DB CR,LF,'SET BAUD <rate>'
DB CR,LF,'SET PORT <port-number>'
DB CR,LF
DB CR,LF,'Baud rate is one of:'
DB CR,LF,' 300 600 1200 4800 9600 19200'
DB CR,LF,'Port number is one of:'
DB CR,LF,' 0-7 : interfacer 3 or 4 port number'
DB CR,LF,' S : System Support I serial port'
DB CR,LF,0
RET
;
; "SET BAUD" processor
;
STBAUD: MVI C,BDPARS ;function code: parse a baudrate
CALL MEX ;let MEX look up code
JC SETERR ;jump if invalid code
CALL PBAUD ;no, try to set it
JC SETERR ;if not one of ours, bomb out
BDSHOW: MVI C,ILP ;inline print
CALL MEX ;display baud
DB 'Baud: ',0
LDA MSPEED ;get current baud rate
MVI C,PRBAUD ;let MEX print it
CALL MEX
RET
;
; SET PORT processor
;
SETPOR: MVI C,SBLANK ;scan to argument
CALL MEX
JC SETERR ;if no arg, bomb out
MVI C,GNC ;else consume it
CALL MEX
SUI '0' ;convert
JC SETERR
CPI 5+1
JNC SETERR
CALL SPA ;set port addresses
MVI C,SBLANK ;any thing more?
CALL MEX
JNC STBAUD ;if so, go parse as baud rate
TELL: MVI C,ILP
CALL MEX
DB CR,LF,'Port: ',0
LDA PORT
ADI '0' ;get port # in ASCII
STA PORTAS
MVI C,ILP
CALL MEX
PORTAS: DB ' ',0
JMP BDSHOW
;
; Initialize channel ... as distributed, this code simply
; sets the default port, default port addresses, and default
; MSPEED (based on MSPTBL table). You might want to modify
; this do do a full channel initialization, including SIO
; setup and baud rate. If so, delete the commented-out code
; in between NITMOD and SPA, and enter your initial baudrate
; just prior to the call on PBAUD. If you do this, you should
; be aware that whenever you enter MEX, the baudrate will be
; set to this default rate (even if a connection is in prog-
; ress at a different rate).
;
NITMOD: MVI A,NPORT ;get initial port number
;
;; De-comment the following for full initialization
;;
;; CALL SPA ;calculate harware port addresses
;; MVI A,?? ;substitute MSPEED baud value for ??
;; CALL PBAUD ;set rate, init channel
;; RET ;end of init block
;
; Calculate hardware status and data port addresses for
; relative port number passed in A.
;
SPA: STA PORT ;save port number
MOV E,A ;port # to DE
MVI D,0 ;index into table
LXI H,PORTBL ;get table of port hardware addresses
DAD D
DAD D
MOV A,M ;fetch status port #
STA SPORT ;set it
INX H
MOV A,M ;fetch data port #
STA DPORT
LXI H,MSPTBL ;get port's MSPEED value
DAD D
MOV A,M ;set MSPEED
STA MSPEED
RET
;
; Port assignment table for each SIO. Each entry
; consists of status-port adrs followed by data-
; port address.
;
PORTBL: DB 0EH,0CH ;port 0 (SIO #1, A)
DB 0FH,0DH ;port 1 (SIO #1, B)
DB 16H,14H ;port 2 (SIO #2, A)
DB 17H,15H ;port 3 (SIO #2, B)
DB 1AH,18H ;port 4 (SIO #3, A)
DB 1BH,19H ;port 5 (SIO #3, B)
;
; This routine sets baud rate passed as MSPEED code in A.
; Returns CY=1 if baud rate not supported (if supported,
; this routine must set the new MSPEED code).
;
PBAUD: PUSH H ;don't alter anybody
PUSH D
PUSH B
MOV E,A ;MSPEED code to DE
MVI D,0
LDA PORT ;get port #
MOV C,A ;to BC
MVI B,0
LXI H,BAUDFL ;offset to flags for this port
DAD B
MOV A,M ;software baudrate supported
ORA A ; for this port?
STC ;prep carry in case not
JZ PBEXIT ;jump if not supported
LXI H,MSPTBL ;yes. offset MSPEED for this port
DAD B
MOV M,E ;store current rate
LXI H,MSPEED ;set MSPEED value also
MOV M,E
LXI H,BAUDTB ;offset into divisor table
DAD D ;indexed by SPEED value
MOV A,M ;fetch divisor
PUSH PSW ;save divisor
PUSH B ;save relative port #
LDA SPORT ;get status port adrs
MOV C,A ;status port adrs to C
MVI B,SIOLEN ;b=length of SIO code
LXI H,SIONIT ;point to init code
DB 0EDH,0B3H ;Z80 OUTIR
POP B ;recall relative port #
LXI H,CTCTBL ;offset to CTC register, this port
DAD B
MOV C,M ;PORT # IN C
MVI A,45H ;SEND COMMAND CODE
DB 0EDH,079H ;Z80 OUTP A instruction
POP PSW ;recall divisor
DB 0EDH,079H ;Z80 OUTP A instruction
ORA A ;return no-errors
PBEXIT: POP B
POP D
POP H
RET
;
; table of CTC divisors for each rate
;
BAUDTB: DB 175 ;110 (not exact, but close enuf)
DB 64 ;300
DB 48 ;450
DB 32 ;600
DB 27 ;710 (not exact)
DB 16 ;1200
DB 8 ;2400
DB 4 ;4800
DB 2 ;9600
DB 1 ;19200
;
; baud rate flags for each SIO port. Set to 0
; for a port that doesn't support software baudrate
; change, 1 for ports that can.
;
BAUDFL: DB 1,1,1,0,0,0 ;6 ports (I have only first 3 connected to CTC)
;
;
; the following table associates each port with a CTC
; hardware address. Valid port addresses must correspond
; with the BAUDFL table above
;
CTCTBL: DB 4,5,6,0,0,0 ;only 3 channels available on 1 ctc
;
; The following table holds MSPEED for each port.
; Since it's not possible to tell divisors exist in
; the CTC prior to bringing up MEX, this table is
; set with defaults, and is filled in with actual
; values as each port gets a SET BAUD command.
;
MSPTBL: DB 5,5,5,5,5,5 ;speed for each port: 1200
;
; Init code for an SIO channel
;
SIONIT: DB 18H ;reset channel
DB 4 ;select write reg 4
DB 44H ;16*clock, 1 stop bit, no parity
DB 5 ;select write reg 5
DB 0EAH ;DTR, 8 bits xmit, TX enabl, RTS
DB 3 ;select write reg 3
DB 0C1H ;8 bits recv, recv enable
SIOLEN EQU $-SIONIT ;length of SIO init code
;
; Port access routines
;
; Input
;
INSP: LDA SPORT ;get status-port adrs
JMP INP1
INDP: LDA DPORT ;get data-port adrs
INP1: STA INP2+1 ;modify the code
INP2: IN 0 ;do the input
RET
;
;
; output status port
;
OUTSP: PUSH PSW ;save the value
LDA SPORT ;get port adrs
JMP OUTT ;on to common code
;
; output data port
;
OUTDP: PUSH PSW ;save the char
LDA DPORT ;get data-port adrs
OUTT: STA OUT1+1 ;modify the code
POP PSW ;recall data byte
OUT1: OUT 0
RET
;
;
PORT: DS 1 ;put your initial port # here
;
DPORT: DS 1 ;data port address
SPORT: DS 1 ;status port address
;
; Clear-to-end-of-screen and clear-screen sequences
;
EOSMSG: DB ESC,'T','$'
CLSMSG: DB 26,'$'
;
;
END
;
