This homework is due 02/22/2006.

1. Problems 7, 15, 19, 23, 30, 31, 36, 46, 61 from Chapter 4

2. For problems 36, 46, 61: Compile the code as “ml /Zi /Fl yourfile.asm”. Debug the .exe file in CodeView, make sure the results are correct. The compiler will produce “yourfile.lst” after compilation. Attach that file to the report.
   
   

3. Fill in the blanks of the following assembly program (back of the page). Compile and debug. While debugging, use button F8 to step into the procedure. Make sure that your result matches the result in the description. Attach the .lst file to the report. Annotate the program with initial content of the registers at the program startup and changes after execution of every instruction. Explain these changes.

4. If you have questions, stop by my office (I can guarantee my availability during office hours, other time you'd have to check that I'm in) or email me.

.MODEL SMALL

.DATA

VAR1 DW 01H, 02H, 03H, 04H, 05H, 06H, 07H, 08H, 09H, 0AH

;Define ten 2-byte variables with the label VAR1

.CODE

.STARTUP

LEA ________, ________ ; Step1: Store the offset of VAR1 into the accumulator

____ ________, ________ ; Step2: Load 10 into register BX

________ ________ ; Step 3: Call procedure ZEROFILL

.EXIT ; Exit to DOS

_______ ______ _______ ; Define a near procedure ZEROFILL

; This procedure expects two arguments

; 1 – register AX must contain the offset in the data memory

; 2 – register BX must contain the number of elements

; Register DI is about to be used and, thus, changed

; If you change it a register in a function, the calling program may
; get confused

; PROCEDURES SHOULD NEVER PERFORM ANY CHANGES

; TO REGISTERS VISIBLE TO THE CALLING PROGRAM

; UNLESS SUCH CHANGE IS AGREED UPON

______ _______ ; Preserve the content of DI on the stack (OS's stack will be used)

; Register CX is about to be used and, thus, changed

______ _______ ; Preserve CX on the stack

____ ______, _____ ; Copy the offset kept in AX into DI

; The default ES segment in the destination of the string transfer instructions

; cannot be overridden by the prefix override DS:

; To have the destination in the data segment we have to
; (1) save ES on the stack (2) copy value from DS into ES

; (3) perform the string operation (4) restore value of the ES from the stack

____ _____ ; Save ES on the stack

____ _____, ____ ; Copy DS into CX

____ _____, ____ ; Copy CX into ES

____ ______, _____ ; Copy the content of register BX into CX (number of elements)

____ _____ ; Save AX on the stack

____ _____, _____ ; Clear AX (load 0 into the AX)

____ _______ ; Use a string transfer instruction to fill the memory with zeros

____ ______ ; Restore content of registers ES, AX, CX and DI by popping them from the
____ ______ ; stack. Make sure that the registers actually contain the same data

____ ______ ; as they had at the entry point of this procedure

____ ______

RET ; return back to the calling function

_______ __________ ; Declare the end of the procedure ZEROFILL

END ; END of the assembly program

; The result: all words in VAR1 should become 0

; At the end of the program all the registers (except AX, BX, IP)

; should have the same values as at the beginning