; Program: T3M-AM2.Z80
; Use: Term3 Modem Overlay
; Written by: David McCord
; Last revised: 05/23/86
;
; Term3 Modem Interface for AMPRO "little board" computers (Z80 DART)
; Uses serial channel 'B' for operation
;
; Completely rewritten for TERM III Phase 2; previous versions did not work.
; Supports baud rates of 300, 1200, 2400, and 9600
;
; Recent changes:
; v2 05/23/86 D. McCord
; redid the mi$init routine.  v1 did not do anything to the DART, which
; wasn't a problem unless you used another comm program (like IMP or
; BYE), which might have left the DART in an undesireable state.
;
; This program, both source code and executable binary code, is
; copyright 1986 Echelon, Inc.  Duplication for non-commercial personal
; use is permitted; all other duplication is prohibited unless authorized
; in writing by the copyright holder.
;
; To use:
;	ZAS T3M-AM1 H			<- make .HEX file output
;	MLOAD MODEM.BIN=T3M-AM1		<- create binary file
;	T3INS INSTALL			<- install into TERM3 modules
;
; Cabling:
;	The AMPRO computer serial ports do not utilize the 'standard'
;	control signals DTR and DCD available on the DART; instead, the
;	RTS and CTS signals (respectively) are used.  This means that the
;	following special cable must be used:
;
;		TERM3 Modem Application Cable
; 	(assumes factory default wiring of serial port B)
;
;		AMPRO			Modem
;	          2  -------------------  3
;		  3  -------------------  2
;		  5  ------------------- 20
;		  7  -------------------  7
;		 20  -------------------  8
;
;	A T3MASTER/T3SERVER special cable is not required.
;
; Equates - first, port assignments
;
dport	equ	88h		; data port for DART channel B
sport	equ	dport+4		; status port for DART channel B
bport	equ	50h		; CTC baud rate generator port
;
bauds	equ	00010111b	; 300, 1200, 2400, 9600 supported
;
	org	600h		; all modem interfaces start at 600h
mi$init:
	jp	smi$init	; set baud rate
mi$istat:
	jp	smi$istat	; check input status
mi$ostat:
	jp	smi$ostat	; check output status
mi$in:
	jp	smi$in		; get input character
mi$out:
	jp	smi$out		; send output character
mi$break:
	jp	smi$break	; send BREAK
mi$cst:
	jp	smi$cst		; check carrier status
mi$sptab:
	db	bauds
;
; see the TERM III manual, pg 7-8 thru 7-10, for discussion of input and
; output parameters for these subroutines.
;
smi$init:
	push	af
	push	hl
	cp	1
	jr	z,set300
	cp	2
	jr	z,set1200
	cp	3
	jr	z,set2400
	cp	5
	jr	z,set9600
noset:
	pop	hl
	pop	af
	xor	a
	ret
;
set300:
	ld	hl,47d0h		; CTC commands for 300 bps
	jr	setspec
set1200:
	ld	hl,4768h		; CTC commands for 1200 bps
	jr	set
set2400:
	ld	hl,4734h		; CTC commands for 2400 bps
	jr	set
set9600:
	ld	hl,470dh		; CTC commands for 9600 bps
setspec:
	ld	a,18h		; reset DART and set clock divider for x32
	out	(sport),a
	ld	a,4
	out	(sport),a
	ld	a,86h
	jr	set1
set:
	ld	a,18h		; reset DART and set clock divider to x16
	out	(sport),a
	ld	a,4
	out	(sport),a
	ld	a,46h
set1:	out	(sport),a
	ld	a,5
	out	(sport),a
	ld	a,6ah
	out	(sport),a
	ld	a,3
	out	(sport),a
	ld	a,0c1h
	out	(sport),a
	ld	a,h			; send command bytes to CTC
	out	(bport),a
	ld	a,l
	out	(bport),a
	pop	hl
	pop	af
	or	a
	ret
;
smi$istat:
	in	a,(sport)
	and	1
	ret	z
	or	0ffh
	ret
;
smi$ostat:
	in	a,(sport)
	and	4
	ret	z
	or	0ffh
	ret
;
smi$in:
	call	smi$istat
	jr	z,smi$in
	in	a,(dport)
	ret
;
smi$out:
	push	af
smi$outloop:
	call	smi$ostat
	jr	z,smi$outloop
	pop	af
	out	(dport),a
	ret
;
smi$break:
	xor	a		; BREAK not supported (although the DART
	ret			; can do it)
;
smi$cst:
	or	255
	ret

;	ld	a,10h
;	out	(sport),a	; reset status
;	in	a,(sport)
;	and	20h
;	ret	z
;	or	0ffh
;	ret
;
; end of this modem interface
;
	db	'Copyright 1986 Echelon, Inc.'