CS301 – Fall 2002

Prof. Hartman

Homework #3

Due Friday, September 27^th by 5:00 pm

1. Write an assembly language program to implement the following C++ code. Do not just duplicate the output – make your code function the same way.

int a, i, z;

cout << "Enter z (z>0): ";

cin >> z;

for (i=0; i<=z; i++)

{

a = i % 2;

if (a == 0)

cout << i << endl;

}

You may use the I/O routines from Carter’s book. Refer to the handout about using NASM with Windows and Visual C++ for links to the I/O files if you don’t have them. Hand in your program listing and a sample run showing z=10. Explain in English what the program does. For full credit you must turn in a well-commented listing including your name and the problem number.

2. For each of the following instructions, indicate the result. Assume BYTE1 is a memory location containing 5Fh:

	Instruction	Before	After
a)	mov cx,25h	; cx = 0000h	cx =
b)	mov cl,0	; cx = 0ffffh	cx =
c)	mov dh,[BYTE1]	; dx = 0beefh	dx =
d)	xchg ah,al	; ax = 1234h	ax =
e)	xor eax,eax	; eax = 12345678h	eax =
f)	inc dl	; dx = 0ffffh	dx =
g)	inc dx	; dx = 0ffffh	dx =

3. a) In what significant way do the following instructions differ in execution?
   
   mov eax, 1234ABCDh
   mov [eax], 1234ABCDh
   
   b) What kind of addressing is involved in the second instruction?