; B5XE-1.INS  -  Xerox 820 insert for BYE5  -  07/17/85
;
;	       Z80-SIO and 8116 baudrate generator
;			  by Irv Hoff
;
;
;	    Note:  This is an insert, not an overlay.
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
; 07/17/85  Written for use with BYE5		- Irv Hoff
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
;
PORT	EQU	04H		; Data port
MDCTL1	EQU	PORT+2		; Modem control port
BRPORT	EQU	00H		; Baud rate generator port
;
MDRCV	EQU	1		; Modem receive ready bit
MDSND	EQU	4		; Modem send ready bit
MDDCD	EQU	8		; Data carrier detect
;
;
; Divisors for the 8116 baudrate generator
;
BD300	EQU	5		; 300 baud
BD1200	EQU	7		; 1200 bps
BD2400	EQU	10		; 2400 bps
;
;
;-----------------------------------------------------------------------
;
; See if we still have a carrier - if not, return with the zero flat set
;
MDCARCK:MVI	A,10H		; Reset status
	OUT	MDCTL1
	IN	MDCTL1		; Get status
	ANI	MDDCD		; Check for carrier
	RET
;.....
;
;
; Disconnect and wait for an incoming call
;
MDINIT:	MVI	A,0		; Setup to write register 0
	OUT	MDCTL1
	MVI	A,18H		; Reset channel
	OUT	MDCTL1
;
	MVI	A,4		; Setup to write register 4
	OUT	MDCTL1
	MVI	A,44H		; Set 16x, 1 stop bit, no parity
	OUT	MDCTL1
;
	MVI	A,3		; Setup to write register 3
	OUT	MDCTL1
	MVI	A,0C1H		; 8 bits, Rx enable
	OUT	MDCTL1
;
	MVI	A,5		; Setup to write register 5
	OUT	MDCTL1
	MVI	A,68H		; DTR off
	OUT	MDCTL1
;
	PUSH	B		; Save in case it's being used elsewhere
	MVI	B,20		; 2 second delay to drop any carrier
;
OFFTI:	CALL	DELAY		; 1 second delay
	DCR	B
	JNZ	OFFTI		; Keep looping until finished
	POP	B		; Restore 'BC'
;
	MVI	A,5		; Setup to write register 5
	OUT	MDCTL1
	MVI	A,0E8H		; Turn DTR back on
	OUT	MDCTL1
;
	 IF	IMODEM		; If using an intellegent modem
	CALL	IMINIT		; Go initialize it now
	 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	MDRCV		; Got a character
	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		; Get status
	ANI	MDSND		; Ready for a character?
	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,5		; Setup to write register 5
	OUT	MDCTL1
	MVI	A,68H		; Turn off DTR until next time
	OUT	MDCTL1
	RET
;.....
;
;
; The following routine sets the baud rate.  BYE5 asks for the maximum
; speed you have available.
;
SETINV:	ORI	0FFH		; Make sure zero flag is not set
	RET
;.....
;
;
SET300:	MVI	A,BD300
	JMP	SETBAUD
;
SET1200:MVI	A,BD1200
	JMP	SETBAUD
;
SET2400:MVI	A,BD2400
;
;
; Sets the baudrate
;
SETBAUD:OUT	BRPORT
	XRA	A		; Say baudrate is ok
	RET
;.....
;
;			       end
------------------------------------------------------------------------
