CS 207 Assignments

Listed in reverse order according to due date.

• Assigned 10/15/97, due on paper on 10/22/97. Do problems 1, 2, 11, 13, 20, 25, 31-33, 41, 44 from Chapter 4 of P & H.
  
  
• Assigned 10/15/97, due on paper on 10/20/97. Do problems 6, 7, 12-17, 20, and 23 from Chapter 3 of P & H.

  In addition, explain in detail the function-calling conventions used by the C compiler "cc" on our SGI's (green, blue, and cyan.mathcs.carleton.edu). Among the questions you might address are:

  • What is the structure of the stack frames? Where do local variables go, and in what order? Where does the return addresss go?
  • How are parameters passed? What if there are more than four of them? What if one is too big to fit in a register? Are floating-point parameters passed in the integer registers?
  • How and where is the return value returned? What if it is too big to fit in a register?
  • Whose responsibility (caller or callee) is it to allocate and deallocate space on the stack for the stack frame?

  The main technique I would use to investigate these questions is to write lots of little C programs and compile them to assembly using "cc -S". If you are not familiar with C, please talk to me. Have fun.
  
  

• Assigned 10/1/97, due on paper on 10/6/97. Do problems 3, 4, 6, 7, 10, 13, and 15 from Appendix B of Patterson and Hennessy.

  Also, design and draw a 1-bit 4-function ALU with the following specifications. The unit should have five input lines: (1) A, a data line, (2) B, another data line, (3) Cin, the carry-in for addition, and (4-5) S0 and S1, a pair of control lines that determine the operation performed by the ALU. There should be two output lines--the result R, and the carry-out Cout. R should depend on the input as follows:

         S1 S0           R
         ============================
         0  0            A
         0  1            A + B + Cin
         1  0            A OR B
         1  1            NOT A      
  

  Cout should be the carry-out if the operation is addition (that is, S1 = 0 and S0 = 1), and 0 otherwise. Note that R is a single bit, so the result R of the addition operation is the right-most bit of the sum of A, B, and Cin.
  
  
• Assigned 9/24/97, due on paper on 9/29/97. Do problems 1-5, 14-20, 22, 32, and 33 from Chapter 2 of Patterson and Hennessy.
  
  
• Assigned 9/15/97, due 9/26/97. Write a PDP8 program that clears as much memory as possible, using no more than 100 (base ten) lines of code. If your program clears all memory, including the program itself, you will earn an A+. Clearing all but one location is worth an A, all but two is worth an A-, etc. Note, by the way, that if you clear all memory, your program will not halt by itself. (What will it do?)
  
  
• Mentioned 9/15/97, due 9/24/97. Write a function for the PDP8 that uses recursion to compute the Nth triangular number. Your main program will get N from the switch register and call a recursive function with N as its parameter. The recursive function, upon return to the main program, will have left the Nth triangular number (T(N) = 1 + 2 + ... + N) in the AC. Don't do this until we talk about it on 9/19.
  
  
• Assigned 9/15/97, due 9/19/97. Write a multiplication subroutine for the PDP8. When the subroutine is called via a JMS call, memory locations 0176 and 0177 should contain the 12-bit two's complement factors to be multiplied, and the AC should contain the address of the first of two memory locations where the 24-bit product will be stored (first the high-order word, and then the low). Your multiplication routine should take both overflow and sign into account.
  
  
• Assigned 9/10/97, due 9/12/97. Assignment #1

Suggested Reading

• 9/10/97 Read Chapter 1 of Patterson and Hennessy.
• 9/24/97 Read Chapter 2 of P and H.
• 10/1/97 Read Appendix B of P and H.
• 10/8/97 Read Chapter 3 and Appendix A of P and H.
• 10/10/97 Read Chapter 4 of P and H.