; B3DP-2.INS  -  BYE3 insert for Datapoint 1560  -  07/30/85
;
;		8251A and 8430 CTC timer 3.6864 MHz
;
;	      Note:  This is an insert, not an overlay
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
; 07/30/85 Restored to original format		- pst
; 11/25/84 Created				- Irv Hoff
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
; The following define the port addresses to use
;
DPORT	EQU	28H		; Modem base port
SPORT	EQU	DPORT+1		; Modem control port
RBPORT	EQU	20H		; Receive speed CTC port
TBPORT	EQU	1AH		; Transmit speed CTC port
;
DAV	EQU	00000010B	; Data available
TBMT	EQU	00000001B	; Transmit buffer empty
DCD	EQU	10000000B	; Data carrier detect
;
RESET	EQU	00111000H	; Framing, overrun and parity errors
;
MDMODE	EQU	10000010H	; Insures 8251 is out of mode, DTR high
MDRSET	EQU	01000010H	; Resets USART for additional commands
MDSET1	EQU	01001110H	; 1 stop bit, no parity, 8 bits, x16
MDSET2	EQU	11001110H	; 2 stop bits, no parity, 8 bits, x16
;
; The following are CTC timer baud rates divisors.
;
BD300	EQU	32		; 9600/300  =  300 bps
BD1200	EQU	8		; 9600/1200 = 1200 bps
BD2400	EQU	4		; 9600/2400 = 2400 bps
;
;-----------------------------------------------------------------------
;
; See if we still have a carrier - if not, return with the zero flag set
;
MDCARCK:IN	SPORT		; Get status
	ANI	DCD		; Check DSR for carrier from modem
	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		; Got a character?
	RZ			; Return if none
	IN	SPORT		; Get status again
	ANI	RESET		; 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
	RET
;
; Renitialize 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 baudrte.  BYE3 asks for the maximum
; speed you have available.
;
SET300:	MVI	B,BD300		; Load 300 baud
	JMP	SETSPD
;
SET1200:MVI	B,BD1200	; Load 1200 baud
	JMP	SETSPD
;
SET2400:MVI	B,BD2400	; Load 2400 baud
;
SETSPD:	MVI	A,47H		; First byte of baudrate
	OUT	RBPORT
	OUT	TBPORT
	MOV	A,B		; Second byte of baudrate
	OUT	RBPORT
	OUT	TBPORT
	XRA	A		; Say it is ok
	RET
;			       end
;-----------------------------------------------------------------------