org 0000h
start: mov r3,#2
start1: mov a,#00h
mov p1,a;LED全亮
acall delay
cpl a;取反
mov p1,a;LED全灭
acall delay
djnz r3,start1
delay: mov r6,#20;子程序延时一秒
MOV TMOD,#10H
MOV TH1,#3CH
MOV TL1,#0B0H
SETB TR1
LOOP1: JBC TF1,LOOP2
AJMP LOOP1
LOOP2: MOV TH1,#3CH
MOV TL1,#0B0H
DJNZ R6,LOOP1
RET
END