Homework 3

22C:122/55:132, Spring 2001

Due Friday Feb 2, 2001, in class

1. Background: Chapter 4 of the classic text, by Bell and Newell Computer Structures is a reprint of the 1946 paper by Berks, Goldstein and Von Neumann that launched the computer age. This paper is in many ways very quaint, but in other ways, very little has changed.

   Part a: What was the word size of the machine described?

   Part b: What was the instruction format?

   Part c: How many registers were available for holding operands?

2. Problem: Use the Iowa Logic Specification Language to construct a finite state machine that obeys the following specification:

   current   input    | next     output
    state  coin wall  | state  stop  turn  go
   -------------------+-----------------------
      x      Y   x    |   -      Y    N    N
    start    N   N    |   -      N    N    Y
    start    N   Y    | left     N    Y    N
    left     N   x    | left1    N    Y    N
    left1    N   x    |   go     N    Y    N
      go     N   N    |  look    N    N    Y
      go     N   Y    | left     N    Y    N
    look     N   x    | look1    N    Y    N
    look1    N   N    |  look    N    N    Y
    look1    N   Y    | left     N    Y    N
   

   Use the table preprocessor and an edge-triggered register to produce a compact description. Turn in your description.

3. A Problem: Describe how you would go about testing a finite state machine such as the above!