电子琴汇编程序

ORG 0000H
  LJMP MAIN
ORG 002BH
  LJMP INT_0
ORG O200H
  MAIN: ACALL KEY ;
ACALL SOUND ;
LJMP  MAIN ;

  KEY:  MOV P2 , #0F0H
MOV P1 , #00H
MOV A ,P1 ;
ORL A ,#0F0H ;
CPL A ;
JNZ IN ;
RET ;

  IN:   NOP
NOP
MOV R2£¬#04H
MOV R4£¬#7FH
MOV R7£¬#00H
  SCAN: MOV A, R4
RL  A
MOV R4 ,A ;
MOV P2£¬A
MOV P1 ,#00H
MOV A,P1 ;
MOV R3£¬#04H
  NEXT: RRC A ;