; B5MT-1.INS - Memotech SDX-512 computer insert for BYE5 - 02/11/86
;
; DART I/O and CTC timer 4.000 MHz
;
; Note: This is an insert, not an overlay.
;
; This version is for the Memotech SDX-512 using channel "B" of the Z80
; DART. The Z80-CTC is used as the baud rate generator.
;
; NOTE: The carrier detect input is checked for "Active low" which
; is quite unusual, and requires a "CMA" in MDCARCK.
;
; Make up a RS232 cable per the instructions below:
;
; Modem Ampro
; ----- -----
; pin 2 - pin 2
; pin 3 - pin 3
; pin 7 - pin 7
; pin 8 - pin 8
; pin 20 - pin 20
;
;
; = = = = = = = = = = = = = = = = = =
;
; 02/11/86 Initial Memotech version - Irv Hoff
;
; = = = = = = = = = = = = = = = = = =
;
;-----------------------------------------------------------------------
;
; Values given are for port 'B'
;
PORT EQU 0DH ; Data port
MDCTL1 EQU 0FH ; Status/control port
BRPORT EQU 0AH ; Baud rate port
;
;
;-----------------------------------------------------------------------
;
; See if we still have a carrier - if not, return with the zero flag set
;
MDCARCK:MVI A,10H ; Reset status
OUT MDCTL1
IN MDCTL1 ; Get status
CMA ; Invert for "active low" for Memotech
ANI 20H ; Check for data carrier
RET
;.....
;
;
; Disconnect and wait for an incoming call
;
MDINIT: MVI A,18H ; Reset channel
OUT MDCTL1
MVI A,4 ; Setup to write register 4
OUT MDCTL1
MVI A,44H ;*1 stop, 8 bits, no parity, 16x
OUT MDCTL1
MVI A,5 ; Setup to write register 5
OUT MDCTL1
MVI A,68H ; Clear RTS causing hangup
OUT MDCTL1
PUSH B ; Save in case it's being used elsewhere
MVI B,20 ; 2 seconds delay to drop any carrier
;
OFFTI: CALL DELAY ; 0.1 second delay
DCR B
JNZ OFFTI ; Keep looping until finished
POP B ; Restore bc
MVI A,3 ; Setup to write register 3
OUT MDCTL1
MVI A,0C1H ; Initialize receive register
OUT MDCTL1
MVI A,5 ; Setup to write register 5
OUT MDCTL1
MVI A,0EAH ; Turn on RTS so modem can answer phone
OUT MDCTL1
;
IF IMODEM ; If using intelligent modem
CALL IMINIT ; Go initialize
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 01H ; Check receive ready bit
RZ ; Return if none
ORI 0FFH ; Otherwise, set the proper flag
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 04H ; Check transmit ready bit
RET
;.....
;
;
; Reinitialize the modem and hang up the phone by dropping DTR and
; leaving it inactive.
;
MDQUIT: IF IMODEM ; If using a smartmodem
CALL IMQUIT ; Tell it to shut down
ENDIF ; IMODEM
;
;
; Called by the main program after caller types BYE
;
MDSTOP: MVI A,5 ; Setup to write register 5
OUT MDCTL1
MVI A,68H ; Clear RTS causing shutdown
OUT MDCTL1
RET
;.....
;
;
; The following routine sets the baudrate. BYE5 asks for the maximum
; speed you have available.
;
SETINV: ORI 0FFH ; Make sure zero flag is not set
RET ; Return
;.....
;
;
SET300: MVI B,BD300 ; Get 300 bps parameters in 'HL'
JMP LOADBD ; Go load them
;
SET1200:MVI B,BD1200
JMP LOADBD
;
SET2400:MVI B,BD2400
JMP LOADBD
;
SET9600:MVI B,BD9600
;
LOADBD: MVI A,47H ; CTC command word
OUT BRPORT
MOV A,B ; Baudrate
OUT BRPORT
XRA A
RET
;.....
;
;
BD300 EQU 64 ; 19200/300 (first half is CTC command)
BD1200 EQU 16 ; 19200/1200
BD2400 EQU 8 ; 19200/2400
BD9600 EQU 2 ; 19200/9600
;
; end
;-----------------------------------------------------------------------
