; CENTRONICS PRINTER DRIVER
; CODE BASED ON YOUR SPECTRUM
; SEP 1984 ISSUE 7
; UPDATED AND IMPROVED
; J.G.HARSTON SEP 1985

ERROR	EQU	#0008	; GENERATE ERROR
POTOKEN	EQU	#0C10	; PRINT TOKEN
REPORTJ	EQU	#15C4	; INVALID DEVICE
BREAK	EQU	#1F54	; TEST BREAK KEY
CHANS	EQU	#5C4F	; CHANNELS AREA

	ORG  #5BB8

; CONNECT TO PRINTER CHANNEL
SETUP	LD   HL,(CHANS)
	LD   DE,15
	ADD  HL,DE	; POINT TO 'P' CHANNEL
	LD   DE,PRTOUT
	LD   (HL),E	; SET OUTPUT ROUTINE
	INC  HL
	LD   (HL),D
	XOR  A
	LD   (RAWOUT),A	; NOT RAW OUTPUT
	RET

; PRINT CHARACTER TO CENTRONICS PORT
PRTOUT	LD   BC,(RAWOUT); C=RAW FLAG
	CP   32
	JR   NC,PRTCHAR	; 32+, ALWAYS PRINT
	CP   14
	JR   NC,PRTLOW	; 14-31, TEST FLAG
	CP   8
	JR   NC,PRTCHAR	; 8-13, ALWAYS PRINT

; 0-7 AND 14-31, IGNORE IF NOT RAW PRINTING
PRTLOW	INC  C		; TEST RAWOUT FLAG
	DEC  C
	RET  Z		; IGNORE IF NOT RAW
PRTCHAR	CP   165
	JR   C,PRTGO	; 32-164, PRINT IT
	INC  C		; TEST RAWOUT FLAG
	DEC  C
	JR   NZ,PRTGO	; PRINT IF RAW
	SUB  165
	JP   POTOKEN	; EXPAND TOKEN

; PRINT CHARACTER TO PRINTER
;  OUT 251: PULSE STROBE  PIN 1
;           BYTE TO WRITE PIN 2-9
;   IN 251: BIT 7: BUSY   PIN 10
;           BIT 6: ACK    PIN 11
;           BIT 5: ERROR  PIN 12
;                  UNUSED PIN 13

PRTGO	PUSH AF
BUSY	IN   A,(251)
	BIT  5,A
	JR   Z,PRTERR	; PRINTER ERROR
	BIT  7,A
	JR   NZ,PRTIT	; PRINTER NOT BUSY
	CALL BREAK	; TEST BREAK KEY
	JR   C,BUSY	; LOOP UNTIL NOT BUSY
PRTERR	RST  ERROR
	DEFB 20		; BREAK

PRTIT	POP  AF
	OUT (251),A
	RET

RAWOUT	DEFB	0

; 72 BYTES