10.4.1 lh-gp16打印机接口.txt

该程序可实现人机的交流

PPRNT1:
SETB 	INT1
JB 		INT1,ERR9				
MOV 	A,#0DH					
MOV  	DPTR,#PRTP			
MOVX 	@DPTR,A					
CLR  	T1
NOP
SETB 	T1;						
MOV  	R3,#40
PPRT1:
SETB 	INT1
JB  		INT1,PPRT2				
DJNZ 	R3,PPRT1					
ERR9:	MOV A,#9
ACALL  	ERRX					
ERR91:
LCALL 	DSPA
JZ   	ERR91
LJMP 	DIPA1					
PPRT2:
MOV 	71H,#99H
MOV  	72H,#0					
SETB 	EX1						
RET
INT1SV:
PUSH 	DPH
PUSH  	DPL
PUSH  	ACC
PUSH  	PSW					
MOV  	DPH,71H
MOV  	DPL,72H					
MOVX 	A,@DPTR					
INC  	DPTR
MOV  	71H,DPH
MOV  	72H,DPL					
CJNE 	A,#3,INT1SD				
CLR  	EX1;禁止INT1				
SJMP 	INT1ED
INT1SD:
MOV 	DPTR,#PRTP
MOVX  	@DPTR,A					
CLR  	T1
NOP
SETB 	T1						
INT1ED:
POP 		ACC
POP  	PSW
POP  	DPL
POP  	DPH						
RETI