; B3ZB-3.INS	- Bye3 / Zorba routines for BYE 	- 08/06/85
;
;	This version is for a 8251a i/o with ctc timer to set speed
;
;	These routines will allow the easy patching of bye3 for any
; type of modem/serial port combination.  certain routines must return
; status flags, so please be careful to set the flags as directed.
;
; This version is for the intel 8251 chip that is hooked up to an
; external modem.
;
;=======================================================================
;
; 08/06/85  Upgraded for bye337 			- pst
; 07/09/85  Modified to work with bye335		- f.e. clayton
; 10/04/82  Routines added, no fuss, mess, or frills.	- pst
;
;=======================================================================
;
; The following define the port address to use.
;
BASEP	EQU	20H		; Modem base port
DPORT	EQU	BASEP		; Data port
SPORT	EQU	BASEP+1		; Status/Control port
CTCCMD	EQU	003H		; Timer control/status port
CTC0	EQU	000H		; Timer 0 (port A)
LSB1200	EQU	0D0H
MSB1200	EQU	000H
;
; the following are sport commands (output these to sport)
;
MODINS	EQU	01001110B	; 8 bits, no parity, 1 stop bit, 16x
OFFINS	EQU	00010000B	; Drop DTR and disable RCV/XMT
ONINS	EQU	00010111B	; Reset flags, send DTR, enable rx & tx
RSTINS	EQU	01000010B	; Reset USART and send DTR
;
; the following are sport status masks
;
TBMT	EQU	00000001B	; Transmitt buffer empty
DAV	EQU	00000010B	; Data available
DCD	EQU	10000000B	; Data carrier detect
FE	EQU	00100000B	; Framing error
OE	EQU	00010000B	; Overrun error
PE	EQU	00001000B	; Parity error
ERR	EQU	00111000B	; Overrun and framing error
;
BD300	EQU	0683H		; 300 baud
BD1200	EQU	01A1H		; 1200 baud
BD2400	EQU	00D0H		; 2400 baud
;
;----------------------------------------------------------------
;
; Initialize modem
;
MDINIT:	MVI	A,OFFINS	; Clear DTR
	OUT	SPORT		; Causing hangup
;
	PUSH	B		; Preserve in case we need it
	MVI	B,20
OFFTI:	CALL	DELAY		; 0.1 second delay
	DCR	B
	JNZ	OFFTI		; Keep looping until finnished
	POP	B		; Restore BC
;
	MVI	A,ONINS		; DTR so that modem can answer phone
	OUT	SPORT
	CALL	SET1200
;
	 IF	IMODEM
	CALL	IMINIT		; Init modem
	 ENDIF
;
	RET
;
; The following routine sets dtr low to turn off the modem when done.
;
MDQUIT:
	 IF	IMODEM
	CALL	IMQUIT
	RET
	 ENDIF
;
MDSTOP:	MVI	A,10H
	OUT	SPORT		; Turn off DTR to hang up the phone
	RET
;
; The following is a routine to determine if there is a character wait-
; ing to be received,  if none, the zero flag will be set, otherwise it
; returns with 255 in register A.  Remember that the system will like you
; a little more if you also mask out framing, parity, and overrun errors.
;
MDINST:	IN	SPORT		; Get status
	ANI	DAV		; Got a character?
	RZ			; Return if none
	IN	SPORT		; Get status again
	ANI	ERR		; Check for framing and overrun
	JZ	MDINST1		; No errors
	MVI	A,ONINS		; Reset error flags
	OUT	SPORT
	XRA	A		; Return false
	RET
;
MDINST1:ORI	255		; We have a character
	RET
;
; The following is a routine to determine if the transmit buffer is
; empty.  If it is, it will return with the zero flag clear.  If the
; transmitter is busy, then it will return with the zero flag set.
;
MDOUTST:IN	SPORT
	ANI	TBMT
	RZ
	ORI	255
	RET
;
; The following is a routine that will check to make sure we still have
; carrier.  If there is no carrier, it will return with the zero flag
; set.
;
MDCARCK:IN	SPORT		; Get status
	ANI	DCD		; Check if carrier is on
	RZ
	ORI	255
	RET
;
; The following is a routine that will input one character from the
; modem port.  If there is nothing there, it will return garbage...
; So use the mdinst routine first.
;
MDINP:	IN	DPORT		; Get character
	RET
;
; The following is a routine that will output one character in register
; a to the modem.  Remember, that is register A, not register C.
;
; ** use MDOUTST first to see if buffer is empty **
;
MDOUTP:	OUT	DPORT		; Send it
	RET
;
; These next routines set the proper baud rates for the modem.
;
SET300:	LXI	H,BD300		; Set 300 baud
	JMP	LOADBD
;
SET1200:LXI	H,BD1200	; Set 1200 baud
	JMP	LOADBD
;
SET2400:LXI	H,BD2400	; Set 2400 baud
	JMP	LOADBD
;
LOADBD:	MVI	A,36H		; Set command mode
	OUT	CTCCMD
	NOP	! NOP !	NOP
	MOV	A,L		; Send LSB of baud
	OUT	CTC0
	NOP	! NOP !	NOP
	MOV	A,H		; Send MSB of baud
	OUT	CTC1
	NOP	! NOP !	NOP
	XRA	A		; Return saying we're ok
	RET
;
;***********************************************************************