CSC231 Homework 2

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Assignment #2

This assignment is due on Wednesday, Sept 24th, at 11:59 p.m. plus 1 minute.

Problem #1

Write a program that displays the following pattern using loops.

**********#
 *********##
  ********###
   *******####
    ******#####
     *****######
      ****#######
       ***########
        **#########
         *##########
        **#########
       ***########
      ****#######
     *****######
    ******#####
   *******####
  ********###
 *********##
**********#

Requirements: your program cannot contain more than 5 int 0x80 instructions!

Store your program in a file called hw2a.asm and submit it as follows:

  submit hw2 hw2a.asm

Problem #2

For this problem you have to debug the executable version of a program and answer two questions.

You can get the executable version of the program by using this command, from your Linux account:

   cp ~thiebaut/public_html/classes/231/hw2 .

(don't forget the dot at the end of the line!)

If you are working off-campus, and you have a linux machine where the utility wget is installed, try this:

   wget http://cs.smith.edu/~thiebaut/classes/231/hw2

and you should get a copy of the program.

Once you're done transfering the program, debug it:

   ddd hw2 &

Question 1

What string of characters is contained in the array that occupies the first 31 bytes of memory when the processor has reached the 3rd NOP instruction of the program?

Question 2

What hexadecimal values are stored in the registers eax, ebx, ecx, and edx when the processor has reached the 3rd NOP instruction of the program?

Write your answers in a file called hw2.txt and submit your file as follows:

  submit hw2 hw2.txt