1. CS 206D Computer Organization
Lab9
CS 111

2. Suppose that AX=7800h BX=1234h CX=91ACh and SP=0100h
Question 2
Suppose that AX=7800h BX=1234h CX=91ACh and SP=0100h
Give the content of AX, BX, CX and SP after executing the following instructions: PUSH AX
PUSH BX
XCHG AX ,CX
POP CX
PUSH AX
POP BX
CS 111

3. Initial: AX=1234h BX=5678h CX=9ABCh SP=0100h
Solution
Initial: AX=1234h BX=5678h CX=9ABCh SP=0100h
PUSH AX ABC FE is pushed
PUSH BX ABC FC is pushed
XCHG AX,CX 9ABC FC
POP CX ABC FE is popped
PUSH AX ABC FC 9ABC is pushed
POP BX ABC 9ABC FE 9ABC is popped
CS 111

4. Write some code to do the following:
Question 2
Write some code to do the following:
Place the top of the stack into AX without changing the stack contents
2) Place the word that is below the stack top into CX, without changing the stack contents. You may use AX.
3) Exchange the top two words on the stack. You may use AX and BX.
CS 111

5. POP AX ;place top of stack into AX PUSH AX ;restore stack contents
Solution
1) Place the top of the stack into AX without changing the stack contents
POP AX ;place top of stack into AX
PUSH AX ;restore stack contents
CS 111

6. POP AX ;place original stack top into AX
Solution
2) Place the word that is below the stack top into CX, without changing the stack contents. You may use AX.
POP AX ;place original stack top into AX
POP CX ;place word that is below original stack top into CX
PUSH CX ;restore word that is below original stack top
PUSH AX ;restore original stack top
CS 111

7. Solution
3) Exchange the top two words on the stack. You may use AX and BX.
POP AX ;place original stack top into AX
POP BX ;place word that is below original stack top into BX
PUSH AX ;place original stack top back on stack
PUSH BX ;place word that was originally below stack top onto stack top
CS 111