File: hw3.txt
Due date: Before 11:59pm Tuesday January 22
Grading: 20 Points total.
To do: Answer the following questions.

(1) What is your name?

(2) Did you work with anyone else on this hw?  Note - this includes
/anyone/ other than Jeff (e.g., your cousin, the GA in the tutoring lab, 
a classmate, ...).  List anyone who you talked to about it, or worked together.

(3) Assembly language.  The adding.151asm file addes up the numbers from 
    1 to 22.  I will describe it either on the HW3 video or in class.
    Make a copy of that file into your home directory on CS, and call it 
    hw3_add.151asm.  Make changes to it so that it adds up the multiples 
    of 7 between 7 and 777.  The final result should be printed.  Just 
    so you, know the correct answer is 43512.

(4) Scratch.  Create your own Scratch program.  Start from an empty project.
    You can look at the built-in Scratch programs for ideas on how to do 
    things, but you need to start your own program from scratch (ha ha).
    You can make the program do anything you want, but it must meet the 
    following requirements.
    a) Work with someone else from this class on the program.  You should 
       make arrangements during class on Thursday on meeting up outside of 
       class to work on the program.  
    b) The program must include at least one loop (those are in the 
       Control section).  The ones that are loops are: forever, repeat, 
       forever if, repeat until, wait until.
    c) The program must use at least one conditional (those are in the 
       Control section also).  The ones that are conditionals are:
       if, if/else, wait until, repeat until, forever if.

    Scratch saves its files with a file extension .sb.  It will add the 
    file extension automatically (at least on Windows it does).  Name your
    scratch file hw3_scratch.sb, and use FileZilla to put it in your home
    directory on CS.

(4) Write here who you worked with on the Scratch program, and describe in a 
    few sentences how it was.  In particular, how much work did each person
    do, and were there any problems.

(5) Hello to Jeff.  Come by my office sometime before my office hours are 
    done on Wednesday.  You can just stop in to say hello, or you can bring
    some questions about the homework and the class.  Plan on spending at 
    least a few minutes chatting or talking about the class.
    The point of this is to ensure you are comfortable coming to ask for 
    help when you need it.  And it will help me to know everyone easier.


Extra Credit, at most 3 points extra
(6) Assembly, testing for primes ...
    a) Make an assembly program to test if one number is a factor of 
       another number.  Save the file as hw3_mod.151asm.  Make it so 
       the program determines whether 13 is a factor of 2567.  The correct
       answer is no.  You can have the program print out 0 if it is a factor, 
       and print out any other number if it is not a factor.

       Here are some examples...  2 is a factor of 12.  2 is not a factor
       of 5.  12 is a factor of 36.  12 is not a factor of 18.

       My suggestion is to think of the problem as follows...  You want to 
       compute the remainder when 2567 is divided by 13.  If the remainder
       is 0, then 13 is a factor.  Otherwise, it is not.  So you can just
       compute the remainder and output that.  

       To compute the remainder, you'll need to know that when the assembler
       does division it actually does "integer division".  That means it 
       divides and rounds down.  So 12 / 3 = 4.  But 12 / 5 = 2.  

    b) If you get part a) correct, you can use that to make a program 
       that tests if a number is prime or not.  A prime number is one that 
       only has itself as a factor.  So, some primes are 3, 5, 7, 11.  Some 
       numbers that are not prime are 4, 6, 8, 10, 12, 15, 21.  

       For this part, make a program called hw3_prime.151asm that tests 
       if the number 2341 is prime or not.  The answer is that it is.  Your
       program should work correctly to test if other numbers are prime
       just by changing 2341 to something else in your program code.

       Here is how I would think about this.  You want to test if any number
       between 2 and 2340 is a factor of 2341.  If any are, it is not 
       prime.  If none are, it is prime.  If you got part a) right, then 
       you can test if any particular number is a factor of 2341.  Now you
       want to "make" a loop to try all numbers between 2 and 2340 as factors.

       The program should output 1 if the number is prime and should output
       0 if it is not prime.