已知SS=0FFA0H,SP=00B0H,先执行两条把1234H和5678H分别进栈的PUSH指令,再执行POP BX指令,试画出堆栈区和SP内容变化的过程示意图(标出存储单元的地址)。
时间: 2024-02-17 15:01:03 浏览: 51
好的,让我来画出堆栈区和SP内容变化的过程示意图:
```
+--------+
| 5678H | <- SP (00AEH)
+--------+
| 1234H |
+--------+
| ... |
+--------+
| ... |
+--------+
| SS |
+--------+
| ... |
| |
+--------+
```
首先,SS=0FFA0H,SP=00B0H,堆栈区的起始地址为SS:SP = 0FFA0H:00B0H = 0FFB0H。
执行PUSH 1234H指令后,将1234H压入堆栈区,SP减2,变为00AEH。
```
+--------+
| 5678H |
+--------+
| 1234H | <- SP (00AEH)
+--------+
| ... |
+--------+
| ... |
+--------+
| SS |
+--------+
| ... |
| |
+--------+
```
执行PUSH 5678H指令后,将5678H压入堆栈区,SP减2,变为00ACH。
```
+--------+
| 5678H | <- SP (00AC)
+--------+
| 1234H |
+--------+
| ... |
+--------+
| ... |
+--------+
| SS |
+--------+
| ... |
| |
+--------+
```
执行POP BX指令后,将堆栈顶部的5678H弹出,赋值给BX寄存器,SP加2,变为00AEH。
```
+--------+
| 5678H |
+--------+
| 1234H | <- SP (00AEH)
+--------+
| ... |
+--------+
| ... |
+--------+
| SS |
+--------+
| ... |
| |
+--------+
BX = 5678H
```
因此,堆栈区的变化过程是:先将1234H压入堆栈区,再将5678H压入堆栈区,最后弹出5678H赋值给BX寄存器。而SP的内容变化过程是:初始值为00B0H,先减2变为00AEH,再减2变为00ACH,最后加2变为00AEH。