CS 206D Computer Organization Lab9 CS 111

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

Initial: AX=1234h BX=5678h CX=9ABCh SP=0100h Solution Initial: AX=1234h BX=5678h CX=9ABCh SP=0100h PUSH AX 1234 5678 9ABC 00FE 1234 is pushed PUSH BX 1234 5678 9ABC 00FC 5678 is pushed XCHG AX,CX 9ABC 5678 1234 00FC POP CX 9ABC 5678 5678 00FE 5678 is popped PUSH AX 9ABC 5678 5678 00FC 9ABC is pushed POP BX 9ABC 9ABC 5678 00FE 9ABC is popped CS 111

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

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

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

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