Question

写汇编语言程序，S1按下时，D1亮S2按下时，D2亮，S3按下时，D3亮，S4按下时，D4亮,用P1口位操作

ORG 0000H
JNB P1.4 , MAIN
SETB P1.0
MAIN: CLR P1.0
JNB P1.5 , LOOP
SETB P1.1
LOOP: CLR P1.1
JNB P1.6 , EXIT
SETB P1.2
EXIT: CLR P1.2
JNB P1.7 , LP1
SETB P1.3
LP1: CLR P1.3
SJMP $
END

Answer 1

;
ORG 0000H
MOV A, P1
SWAP A
ORL A, #0F0H
MOV P1, A
SJMP 0000H

END

Answer 2

ORG 0000H
LJMP MAIN
ORG 0030H
MAIN:
MOV A,P1
ANL A,#0F0H
MOV B,A
SWAP A
XCH A,B
ORL A,B
MOV P1,A
SJMP MAIN
END