存储器中的变量未由存储更新为该符号 [英] Variable in memory not updated by a store to that symbol

问题描述

当我运行emu8086时，此结果返回给我0 ..为什么?

When I run the emu8086, this result(ans) return to me 0 ..Why ?

data segment
ans dw ? 
ends

stack segment
    dw   128  dup(0)
ends

code segment
start:
mov ax,@data
mov dx,ax
mov ax,2
mov bl,2
mul bl
mov ans,ax
mov ax, 4c00h
int 21h  
ends
end start

推荐答案

mov ax,@data
mov dx,ax

这部分代码必须设置DS段寄存器.
您打错了字，而是写了DX！

This part of the code must setup the DS segment register.
You made a typo and wrote DX instead!

mov ax, @data
mov ds, ax

由于此错误，AL * BL乘法(4)的结果仍由mov ans,ax写入内存中，但未将其写入数据段 .它覆盖了ProgramSegmentPrefix的第一个单词，因为这是DS所指向的位置.

Because of this error, the result of your AL * BL multiplication (4) was still written in memory by mov ans,ax but it didn't make it to the data segment. It overwrote the first word of the ProgramSegmentPrefix because that was where DS was pointing at.

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