; Program: T3M-HI2.Z80
; Use: Term3 Modem Overlay
; Written by: David McCord
; Last revised: 04/02/87
;
; Latest Revisions:
; dmm   4/02/87 v2.0
;	Reworked baud rate setting, adding support for 9.216MHz and 12.288MHz
; clock rates.  Also added equate for selection of which serial port will
; be used, ASCI0 or ASCI1.  You must set the clock rate equates and ASCI
; equates appropriately (below) before assembly!
;
; dmm	4/21/86	v1.0
;	Originally MODEMH80.Z80; renamed to conform to new naming standards
; for TERM III interface files (T3M-xx#.Z80 for "modem interfaces";
; T3T-xx#.Z80 for "telephone interfaces"; and T3C-xx#.Z80 for combined
; modem AND telephone interfaces (as with the MOSART)).
;	Fixed a minor bug in the mi$init routine.
;
; Term3 Modem Interface for SB180/HD64180
; Uses HD64180 ASCI 0 (modem port on SB180)
;
; Modified from original MSB180.LIB file 03-21-86 by D. McCord
; Supports baud rates up to 38.4Kbps (max 19.2Kbps for 9.216MHz clock)
;
; This program, both source code and object code, is
; copyright 1986 Echelon, Inc.  Duplication for non-commercial personal
; use is permitted; all other duplication is prohibited unless authorized
; in writing by copyright holder.
;
; To use:
;	ZAS T3M-HI2 H			<- make .HEX file output
;	MLOAD MODEM.BIN=T3M-HI2		<- create binary file
;	T3INS INSTALL			<- install into TERM3 modules
;
; Cabling:
;	Because of the HD64180's internal logic (which will not
;	allow sending characters when the carrier detect input is
;	false), a special cable must be used.  Also, a different cable
;	is used for a T3SERVER/T3MASTER application.
;
;		TERM3 Modem Application Cable
;
;		SB180			Modem
;		  1 --------------------- 1
;		  2 --------------------- 2
;                 3 --------------------- 3
;                 4 --------------------- 4
;                 5 --------------------- 8	<- note
;		  6 --------------------- 6
;		  7 --------------------- 7
;		  8 --------------------- 5	<- note
;		 20 --------------------- 20
;
;	  TERM3 T3MASTER/T3SERVER Application Cable (Tested with
;   AMPRO Little Board and Magnum Digital PRO-180 as "Other Computer")
;
;		SB180(Master)	Other Computer(Server)
;		  1 --------------------- 1
;		  2 --------------------- 2
;		  3 --------------------- 3
;		  4 --+
;                 5 --| <- Note: 4, 5, & 8 tied together
;                 8 --+
;		  7 --------------------- 7
;
; define "yes" and "no"
;
no	equ	0
yes	equ	not no
;
; User-select equates - select "yes" to only one clock rate
;
c6144kHz	equ	yes	;  6.144MHz
c9216kHz	equ	no	;  9.216MHz
c12288kHz	equ	no	; 12.288MHz
;
; select ASCI 0 (modem port on SB180) or ASCI 1
;
asci0		equ	no
asci1		equ	yes
;
; Non-changeable equates
;
base	equ	600h		; base of Modem Interface in T3 tools
	 if	asci0
cntla	EQU	0		; ASCI Control Register A Channel 0
cntlb	EQU	2		; ASCI Control Register B Channel 0
stat	EQU	4		; ASCI Status Register Channel 0
tdr	EQU	6		; ASCI Transmit Data Register Channel 0
rdr	EQU	8		; ASCI Receive Data Register Channel 0
	 endif
	 if	asci1
cntla	EQU	1		; ASCI Control Register A Channel 1
cntlb	EQU	3		; ASCI Control Register B Channel 1
stat	EQU	5		; ASCI Status Register Channel 1
tdr	EQU	7		; ASCI Transmit Data Register Channel 1
rdr	EQU	9		; ASCI Receive Data Register Channel 1
	 endif
CTS	EQU	00100000B	; Clear-to-send input (pin 5)
DCD	EQU	00000100B	; Data Carrier detect bit (pin 8)
RDRF	EQU	10000000B	; RECEIVE DATA REGISTER FULL
TDRE	EQU	00000010B	; TRANSMIT DATA REGISTER EMPTY
;
; Term3 Baud Rate definitions
;
; chart of baud rates vs. clock speed for 64180
;
;       6.144MHz clock      9.216MHZ clock      12.288MHz clock
;           PS  DR  SS          PS  DR  SS           PS  DR  SS
; 38400      0   0   0           -- na --             0   0   1
; 19200      0   0   1           1   0   0            0   0   2
;  9600      0   0   2           1   0   1            0   0   3
;  4800      0   0   3           1   0   2            0   0   4
;  2400      0   0   4           1   0   3            0   0   5
;  1200      0   0   5           1   0   4            0   0   6
;   300      0   1   5           1   0   6            0   1   6
;
	 if	c6144kHz
bauds	equ	01111111b	; this modem interface supports 300, 1200,
				; 2400, 4800, 9600, 19200, 38400
	 endif
;
	 if	c9216kHz
bauds	equ	00111111b	; this modem interface supports 300, 1200,
				; 2400, 4800, 9600, 19200
	 endif
;
	 if	c12288kHz
bauds	equ	01111111b	; this modem interface supports 300, 1200,
				; 2400, 4800, 9600, 19200, 38400
	 endif
;
	.HD64	; enable Hitachi Mnemonics
	org	base
;
; Jump Table
;
	JP	INIT		; m1$init
	JP	ISTAT		; M1$istat
	JP	OSTAT		; m1$ostat
	JP	INP		; m1$in
	JP	OUTP		; m1$out
	JP	BREAK		; m1$break
	JP	CST		; m1$cst
AVAILBD:
	DB	bauds		; set via EQUate above
;
; initialization.  Set baud rate, but leave DTR (really RTS) high
;
INIT:
	 if	c9216kHz
	cp	7		; we can't do 38.4K @ 9.216MHz
	jr	z,noset
	 endif
	OR	A		; is entry parameter 0?
	JR	NZ,SETB		; if yes, fall thru to no set
NOSET:	POP	AF
	XOR	A		; return "not supported"
	RET
SETB:	PUSH	HL		; save regs
	PUSH	DE
	LD	HL,[b300-1]	; get base of baud table
	LD	D,0		; prep for subsequent add
	LD	E,A		; index into baud rate table
	ADD	HL,DE		; add index to base
	LD	D,(HL)		; get desired byte
	OUT0	(cntlb),D	; send it
	POP	DE
	POP	HL
	OR	A		; return proper indication to calling routine
	RET
;
; Input status.  Returns Z and A=0 if nothing waiting.
;
ISTAT:	CALL	IISTAT
	AND	RDRF
	RET	Z
	LD	A,0FFH
	RET
;
; Read stat twice, as per Hitachi manual
;
IISTAT:	IN0	A,(stat)
	IN0	A,(stat)
	OR	A
	RET
;
; Check state of CTS* and return A=0 and Z if CTS is true.
;
CKCTS:	IN0	A,(cntlb)
	AND	CTS
	RET	Z
	LD	A,0FFh
	RET
;
; Output status.  Returns Z and A=0 if not ready to send.
;
OSTAT:	CALL	IISTAT		; GET STATUS REG
	AND	TDRE
	JR	Z,DOCTS
OST1:	LD	A,0FFH
	OR	A
	RET
;
; TDRE is false.  Is it because CTS is false?
;
DOCTS:	CALL	CKCTS		; look at CTS (really modem carrier)
	JR	NZ,OST1		; CTS is false; goto faking "OK to send"
	XOR	A		; return "not ready" indication
	RET
;
; Recieve a character
;
INP:	CALL	ISTAT
	JR	Z,INP
	IN0	A,(rdr)
	RET
;
; Send a character
;
OUTP:	PUSH	AF
	CALL	CKCTS		; check CTS
	JR	NZ,DELAY	; if CTS is false, delay before sending
OUTP1:	CALL	OSTAT
	JR	Z,OUTP1
OUTP2:	POP	AF		; return point from "CTS false" delay
	OUT0	(tdr),A
	RET
;
; This delay routine is used when CTS (pin 5 on SB180) is false.  Hitachi
; designed the ASCI 0 to lock the TDRE status bit false when CTS is false,
; yet the ASCI 0 can still send characters under this circumstance.  However,
; because TDRE is always false, we must manually delay after each character
; to prevent over-running the serial port.  Worst case for this delay is
; 300 bps, where each character (10 bits) is 33.3 milliseconds.  This
; delay subroutine delays about 36 milliseconds in an HD64180 system at
; the selected clock rate.
;
	 if	c6144kHz
wait	equ	12
	 endif
	 if	c9216kHz
wait	equ	18
	 endif
	 if	c12288kHz
wait	equ	24
	 endif
DELAY:	LD	A,wait		; 6 T-states
D1:	PUSH	AF		; 11 T-states			|
	LD	A,0FFh		; 6 T-states			|
D2:	EX	(SP),HL		; 16 T-states		| 72 if	|
	EX	(SP),HL		; 16			| true,	| 18398 if
	EX	(SP),HL		; 16			| 70 if	|  true,
	EX	(SP),HL		; 16			| false	| 18396 if
	DEC	A		; 4			|	|  false
	JR	NZ,D2		; 8 if true, 6 if false	|	|
	POP	AF		; 9				|
	DEC	A		; 4				|
	JR	NZ,D1		; 8 if true, 6 if false		|
	JR	OUTP2		; return and force send of character
;
; process BREAK request
;
BREAK:	XOR	A
	RET		;NO BREAK AVAILABLE
;
; check carrier status
;
CST:	CALL	CKCTS		; check CTS (really modem carrier, via
	JR	Z,CST1		; the special cable discussed above
	XOR	A		; NO CARRIER
	RET
CST1:	LD	A,0FFH
	OR	A
	RET
;
; Baud Rate Tables
;
	 if	c6144kHz
;
; HD64180 commands to set baud rates @ 6.144 MHz clock
;
b300:	db	00001101b	; no PS, sampling rate 64, divide ratio 32
b1200:	db	00000101b	; no PS, sampling rate 16, divide ratio 32
b2400:	db	00000100b	; no PS, sampling rate 16, divide ratio 16
b4800:	db	00000011b	; no PS, sampling rate 16, divide ratio 8
b9600:	db	00000010b	; no PS, sampling rate 16, divide ratio 4
b19200:	db	00000001b	; no PS, sampling rate 16, divide ratio 2
b38400:	db	00000000b	; no PS, sampling rate 16, divide ratio 1
	 endif
	 if	c9216kHz
;
; HD64180 commands to set baud rates @ 9.216 MHz clock
;
b300:	db	00100110b	; PS, sampling rate 16, divide ratio 64
b1200:	db	00100100b	; PS, sampling rate 16, divide ratio 16
b2400:	db	00100011b	; PS, sampling rate 16, divide ratio 8
b4800:	db	00100010b	; PS, sampling rate 16, divide ratio 4
b9600:	db	00100001b	; PS, sampling rate 16, divide ratio 2
b19200:	db	00100000b	; PS, sampling rate 16, divide ratio 1
	 endif
	 if	c12288kHz
;
; HD64180 commands to set baud rates @ 12.288 MHz clock
;
b300:	db	00001110b	; no PS, sampling rate 64, divide ratio 64
b1200:	db	00000110b	; no PS, sampling rate 16, divide ratio 64
b2400:	db	00000101b	; no PS, sampling rate 16, divide ratio 32
b4800:	db	00000100b	; no PS, sampling rate 16, divide ratio 16
b9600:	db	00000011b	; no PS, sampling rate 16, divide ratio 8
b19200:	db	00000010b	; no PS, sampling rate 16, divide ratio 4
b38400:	db	00000001b	; no PS, sampling rate 16, divide ratio 2
	 endif
;
; End of this modem interface
;
	db	'copyright 1987 Echelon, Inc.'