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; B5SB-2.INS - Intertec Superbrain overlay file for BYE5 - 03/17/86
;
; BYE5 routine for 8251A and BR1941 baudrate generator
;
; NOTE: This is an insert, not an overlay.
;
;
; = = = = = = = = = = = = = = = = = =
;
; 03/17/86 Added some missing equates - Irv Hoff
; 07/17/85 Written for use with BYE5 - Irv Hoff
;
; = = = = = = = = = = = = = = = = = =
;
; The following define the port addresses to use
;
PORT EQU 58H ; Modem base port
MDCTL1 EQU 59H ; Modem control port
BRPORT EQU 60H ; BR1941 baudrate generator port
;
MDMODE EQU 82H ; Insures 8251 is out of mode, DTR high
MDRSET EQU 42H ; Resets USART for additional commands
MDSET1 EQU 4EH ; 1 stop bit, no parity, 8 bits, x16
MDSET2 EQU 0CEH ; 2 stop bits, no parity, 8 bits, x16
;
;
; Baudrate table
;
BD300 EQU 57H ; Modem 300, printer 1200
BD1200 EQU 77H ; Modem 1200, printer 1200
BD2400 EQU 0A7H ; Modem 2400, printer 1200
BD9600 EQU 0E7H ; Modem 9600, printer 1200
;
;
;-----------------------------------------------------------------------
;
; See if we still have a carrier - if not, return with the zero flag set
;
MDCARCK:IN MDCTL1 ; Get status
ANI 80H ; Check DSR for carrier from modem
RET
;.....
;
;
; Disconnect and wait for an incoming call.
;
MDINIT: MVI A,10H ; Clear DTR
OUT MDCTL1 ; Causing hangup
PUSH B ; Preserve in case we need it
MVI B,20 ; 2 seconds to drop DTR

OFFTI: CALL DELAY ; 0.1 second delay
DCR B
JNZ OFFTI ; Keep waiting until carrier drops
POP B ; Restore BC
MVI A,MDMODE ; Insure 8251 is out of mode
OUT MDCTL1
XTHL ; Delay a little
XTHL ; Delay a little
MVI A,MDRSET ; Reset the 8251A for new command
OUT MDCTL1
XTHL
XTHL
MVI A,MDSET1 ; Set stop pulse, no parity 8 bits, x16
OUT MDCTL1
XTHL
XTHL
MVI A,17H ; Reset error flags, RCV, DTR, TX ready
OUT MDCTL1
XTHL
XTHL
;
IF IMODEM
CALL IMINIT ; Initialize smartmodem
ENDIF ; IMODEM
;
RET
;.....
;
;
; Input a character from the modem port
;
MDINP: IN PORT ; Get character
RET
;.....
;
;
; Check the status to see if a character is available. If not, return
; with the zero flag set. If yes, use 0FFH to clear the flag.
;
MDINST: IN MDCTL1 ; Get status
ANI 02H ; Check the receive ready flag
RZ ; Return if none
IN MDCTL1 ; Get status again
ANI 30H ; Check for framing and overrun
JZ MDINST1 ; No errors
MVI A,17H ; Reset error flags
OUT MDCTL1
XRA A ; Return false
RET
;...
;
;
MDINST1:ORI 0FFH ; We have a character
RET
;.....
;
;
; Send a character to the modem
;
MDOUTP: OUT PORT ; Send it
RET
;.....
;
;
; See if the output is ready for another character
;
MDOUTST:IN MDCTL1
ANI 01H ; Check transmit ready flag
RET
;.....
;
;
; Reinitialize the modem and hang up the phone by dropping DTR and
; leaving it inactive.
;
MDQUIT: IF IMODEM
CALL IMQUIT
ENDIF ; IMODEM
;
;
; Called by the main program after caller types BYE
;
MDSTOP: MVI A,10H ; DTR low hangs up phone, keep DTR low
OUT MDCTL1 ; so will not auto-answer at any time
RET
;.....
;
;
; The following routine sets the baudrate.
;
SETINV: MVI A,0FFH
ORA A ; Make sure the Zero flag isn't set
RET
;.....
;
;
SET300: MVI A,BD300 ; Load 300 baud
JMP SETSPD
;
SET1200:MVI A,BD1200 ; Poke in 1200 bps
JMP SETSPD
;
SET2400:MVI A,BD2400 ; Load 1200 bps
;
SETSPD: OUT BRPORT
XRA A ; Say it is ok
RET
;.....
;
; end
;-----------------------------------------------------------------------