b15-1.asm

汇编语言的设计

	ORG 	0000H
     	LJMP 	MAIN
     	ORG 	000BH
     	LJMP 	TT0
     	ORG     1000H	
MAIN:	SETB 	P1.0
	MOV 	R0,21H
     	MOV 	TMOD,#01H
     	MOV 	TL0,22H
     	MOV 	TH0,23H
     	SETB 	TR0
     	SETB 	ET0
     	SETB 	EA
L1:  	CJNE 	R0,#00H,L2
     	CPL 	P1.0
     	MOV 	A,20H
     	SUBB 	A,21H
     	MOV 	21H,A
     	MOV 	R0,A
L2:  	AJMP 	L1
TT0:    MOV 	TL0,22H
     	MOV 	TH0,23H
     	DEC 	R0
     	RETI
	END