CSC270 Homework 3 2016

--D. Thiebaut (talk) 20:13, 9 February 2016 (EST)

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This assignment is due on Thursday 2/18/16, at 11:55 p.m. You can work on this assignment individually or in a pair. Submit your answer as a pdf, on Moodle.

Problem 1

Below is a 32-bit binary adder. We have seen it in class. It outputs a+b, where a is represented by a₃₁...a₀, and b by b₃₁...b₀.

Question 1

Using this design as inspiration, design a 32-bit subtraction circuit, that will output a-b, if a and b are the two integers whose bits are shown in the diagram.

Hints: a-b is really a + the 2's complement of b.

Question 2

Design a circuit that has 3 input sets: a, a 32-bit signal, b, another 32-bit signal, and x, a 1-bit signal. The circuit has 33 outputs. When x is 0, the circuit outputs a+b. When x is 1, the circuit outputs a-b.