CS 61C (Fall 2007)

Quiz 22

Two questions, submit as "quiz22".  Due 2:45pm before lecture 10/19/2007.


1.

Which of the following are XOR gates be used for, select as many as apply. You may wish to write out the truth table for the XOR gate, and examine it.
  1. Conditional Inverter
  2. Adder Without Carry
  3. Comparator

2.

Provide a simplified Boolean expression that computes the output x = (a&b) | (a & ((b|~a) | ~b)) = ab+(a((b+~a)+~b)) (given in Verilog and Boolean equation syntax) to the input values a and b. Your expression should be immediately translatable to a circuit with at most three gates. The gates of the circuit should include only (one-input) NOT and two-input AND and two-input OR gates. You may give you answer in either Boolean algebra syntax or Verilog syntax, whichever is more comfortable for you.