Intel 9800758-02 manual Figure F-S. Sample User-Written 1/0 Driver Routine

BASIC-80 RMX/80 BASIC-SO

USER TERMINAL HANDLER TO OUTPUT FOR FILE :L1:

NAME	BQUSER
PUBLIC	BQUSER
EXTRN	BQOPNX,RQSEND,RQWAIT,RQOUTX
CSEG

;WAIT FOR MESSAGE AT BQOPNX

;OPEN AND CLOSE ARE IGNORED

BQUSER:	LXI	B,BQOPNX		:EXCHANGE FOR USER OPEN
LXI	0,0	;WAIT FOREVER
CALL	RQWAIT
PUSH	H	;MESSAGEADOR
LXI	0,4	;OFFSET OF TYPE
DAD	0
MOV	A,M	;MESSAGE TYPE
LXI	D,S	;STATUS IS AT OFFSET 9
DAD	0
CPI	14	;CLOSE TYPE
JZ	ZSTAT		;ZEROSTATUSANOQUIT
CPI	15	;OPEN STAT
JNZ	NOTOPN		;NOT AN OPEN REQUEST
PUSH	H	;SAVE STATUS ADOR
LXI	0,6	ADD 6 TO GET LOCATION
DAD	0	;OFAFREXCHANGE
LXI	O,BQOPNX ;OPEN EXCHANGE ALSO USED FOR WRITE MESSAGES
MOV	M,E	;LOW BYTE AFR
INX	H	,
MOV	M,O	;HI BYTE AFR
POP	H	;RESTORE STATUS POINTER
JMP	ZSTAT		;AND ZERO STATUS
NOTOPN:
CPI	12	;WRITETYPE
JZ	WRITE
; BAD MESSAGE TYPE - RETURN ERROR STATUS
MVI	M,18	;STATUS-UNRECOGNIZEDTYPE
JMP	ERRRET ;RETURN MESSAGE AND QUIT
; PASS MESSAGE ON TO TH
WRITE:	LXI	B,RQOUTX		;TH OUTPUT EXCH
POP	0	;MESSAGE AOOR
CALL	RQSEN~SENOMESSAGE
JMP	BQUSER ;WAIT FOR MORE

,

;ZERO STATUS AND RETURN MESSAGE

ZSTAT: XRA A

MOV	M,A	;LOW BYTE OF STATUS
ERRRET:	INX	H
MOV	M,A	;HI BYTE OF STATUS
; RETURN MESSAGE
DCX	H	;BACKUPTO
OCX	H		RESPONSE EXCH
MOV	B,M		;HI BYTE OF RESP EXCH
DCX	H
MOV	C,M		;LOW BYTE
POP	0	;MESSAGEAODR
CALL	RQSENO		RETURN MESSAGE
JMP	BQUSER		;WAIT FOR MORE
END

Figure F-S. Sample User-Written 1/0 Driver Routine

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