ORG 00H AJMP START ORG 03H AJMP INT0SUB ORG 0030H START: MOV IE,#10000001B MOV TCON, #00000001B MOV SP,#20H MOV A,#0FEH RTT: RR A MOV P0,A ACALL DELAY AJMP RTT DELAY: MOV R3,#00H DEL: MOV R4,#00H DJNZ R4,$ DJNZ R3,DEL RET INT0SUB: PUSH PSW PUSH A SETB RS0 CLR RS1 MOV R1,#09H LOOP: MOV A,#0H MOV P0,A ACALL DELAY MOV A,#0FFH MOV P0,A DJNZ R0,LOOP POP A POP PSW RETI END