; B3SB-2.INS - Intertec Superbrain overlay file for BYE3 - 08/01/85
;
; BYE3 routine for 8251A and BR1941 baudrate generator
;
; NOTE: This is an insert, not an overlay.
;
; = = = = = = = = = = = = = = = = = =
;
; The following define the port addresses to use
;
DPORT EQU 58H ; Data port
SPORT EQU DPORT+1 ; Status/Control port
BRPORT EQU 60H ; CTC baudrate port
;
; Baudrate table
;
BD300 EQU 057H ; Modem 300, printer 1200
BD1200 EQU 077H ; Modem 1200, printer 1200
BD2400 EQU 0A7H ; Modem 2400, printer 1200
;
; Status port masks
;
TBMT EQU 00000001B ; Transmitt buffer empty
DAV EQU 00000010B ; Data available
DCD EQU 10000000B ; Data carrier detect
;
;-----------------------------------------------------------------------
;
; See if we still have a carrier - if not, return with the zero flag set
;
MDCARCK:IN SPORT ; Get status
ANI DCD
RZ
ORI 255
RET
;
; Disconnect and wait for an incoming call.
;
MDINIT: MVI A,10H ; Clear DTR
OUT SPORT ; 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 SPORT
XTHL ; Delay a little
XTHL ; Delay a little
MVI A,MDRSET ; Reset the 8251A for new command
OUT SPORT
XTHL
XTHL
MVI A,MDSET1 ; Set stop pulse, no parity 8 bits, x16
OUT SPORT
XTHL
XTHL
MVI A,17H ; Reset error flags, RCV, DTR, TX ready
OUT SPORT
XTHL
XTHL
;
IF IMODEM
CALL IMINIT ; Initialize smartmodem
ENDIF ; IMODEM
;
RET
;
; Input a character from the modem port
;
MDINP: IN DPORT ; 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 SPORT ; Get status
ANI DAV ; Check the receive ready flag
RZ ; Return if none
IN SPORT ; Get status again
ANI 30H ; Check for framing and overrun
JZ MDINST1 ; No errors
MVI A,17H ; Reset error flags
OUT SPORT
XRA A ; Return false
RET
;
MDINST1:ORI 255 ; We have a character
RET
;
; Send a character to the modem
;
MDOUTP: OUT DPORT ; Send it
RET
;
; See if the output is ready for another character
;
MDOUTST:IN SPORT
ANI TBMT ; Check transmit ready flag
RZ
ORI 255
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 SPORT ; so will not auto-answer at any time
RET
;
; The following routine sets the baudrate. BYE3 asks for the maximum
; do not support the particular rate, then simply put in a JMP to
;
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
;-----------------------------------------------------------------------
