这个不是51的汇编 不过差不多 把指令稍改下就好
不会的话加QQ 64767563
;=======================================
;MUL2BYTE
;RENTER R1R2*R3R4
;EXIT =R5R6R7R8
;=======================================
MOV A,#00H
MOV R5,A
MOV R6,A
MOV R7,A
MOV R8,A
MOV A,R2 ;R2*R4
MUL A,R4
MOV R8,A
MOV A,R
MOV R7,A
MOV A,R4 ;R4*R1
MUL A,R1
ADD A,R7
MOV R7,A
MOV A,#00H
ADC A,R
MOV R6,A
MOV A,R2 ;R3*R2
MUL A,R3
ADD R7,A
MOV A,R
ADC R6,A
MOV A,#00H
ADC R5,A
MOV A,R3 ;R3*R1
MUL A,R1
ADD R6,A
MOV A,#00H
ADC A,R
ADC R5,A
JMP $