; B3H8-2.INS - Heath H89 insert for BYE3 - 		07/30/85
;
;	     8250 I/O with built-in baudrate generator
;
;	      Note:  This is an insert not an overlay
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
; 07/30/85  Restored original format			- pst
; 07/21/85  Fixed LOADBD code				- Bill Wood
; 06/16/85  Put in missing RET just before MDINP.       - Bill Wood	
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
; The following define the port address to use.
;
DPORT	EQU	0D8H		; Data port
LCPORT	EQU	DPORT+3		; Line control register
MCPORT	EQU	DPORT+4		; Modem control register
LSPORT	EQU	DPORT+5		; Line status register
MSPORT	EQU	DPORT+6		; Modem status register
;
DAV	EQU	00000001B	; Data available
TBMT	EQU	00100000B	; Transmit buffer empty
DCD	EQU	10000000B	; Data carrier detect
;
BD300	EQU	0180H		; 300  baud
BD1200	EQU	0060H		; 1200 baud
BD2400	EQU	0030H		; 2400 baud
;
;-----------------------------------------------------------------------
;
; See if we still have a carrier - if not, return with the zero flag set
;
MDCARCK:IN	MSPORT		; Get modem status
	ANI	DCD		; Check for carrier
	RZ
	ORI	255
	RET
;
; Disconnect and wait for an incoming call
;
MDINIT:	XRA	A		; Shut off DTR & RTS
	OUT	MCPORT		; Which turns off modem.
;
	PUSH	B		; Preserve since we need it
	MVI	B,20		; 2 seconds delay to drop any carrier
OFFTI:	CALL	DELAY		; .1 second delay
	DCR	B
	JNZ	OFFTI		; Loop until done
	POP	B		; Restore BC
;
	MVI	A,03H		; 8-level, 1 stop bit, no parity
	OUT	LCPORT		; Line control register (03=1, 07=2)
	MVI	A,03H		; Turn on DTR and RTS & wait for call
	OUT	MCPORT
;
	 IF	IMODEM
	CALL	IMINIT		; Init smartmodem
	 ENDIF			; IMODEM
;
	RET			; Added in B3H8-1.INS to make function
;
; 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	LSPORT		; Get status
	ANI	DAV		; Check receive ready bit
	RZ			; Return if not ready
	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	LSPORT
	ANI	TBMT		; Check transmit ready bit
	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:	XRA	A		; Turn off DTR (in case NORING was on)
	OUT	MCPORT
	RET
;
; The following routine sets the baudrate.  BYE3 asks for the maximum
; speed you have available.
;
SET300:	LXI	H,BD300		; Get 300 baud parameters in HL
	JMP	LOADBD		; Go load them
;
SET1200:LXI	H,BD1200
	JMP	LOADBD
;
SET2400:LXI	H,BD2400
;
LOADBD:	DI			; Turn off interrupts for initialization
	XRA	A
	OUT	DPORT+1		; Interrupt enable register
	MVI	A,80H		; Insure out of mode to set baud rate
	OUT	LCPORT		; Line control register
	MOV	A,L		; Get least significant baud rate byte
	OUT	DPORT
	MOV	A,H		; Get most signifcant baud rate byte
	OUT	DPORT+1
	MVI	A,03H		; 8-level, 1 stop bit, no parity
	OUT	LCPORT		; Line control register (03=1, 07=2)
	MVI	A,01H		; Set 'DTR' nromal
	OUT	MCPORT		; Modem control register
	EI			; Restore interrupts to normal
	RET
;			       end
;-----------------------------------------------------------------------