# CESC 222-Digital Circuit Design

CESC 222-Digital Circuit Design

## 3.1 Design problem

Problem 1

A combinational logic circuit has four inputs (A, B, C, and D) and one output Z. The output is 1 if the input has three consecutive 0’s or three consecutive 1’s. For example, if A = 1, B = 0, C = 0, and D = 0, then Z = 1, but if A = 0, B = 1, C = 0, and D = 0, then Z = 0. Design the circuit using one four-input OR gate and four three-input AND gates. Use SimUaid to simulate your circuit design. Submit a truth table and Boolean expressions and also submit a schematic of your final circuit generated from SimUaid.

Problem 2

If assigned by your instructor work the following problem:

Design a combinational logic circuit which has one output Z and a 4-bit input ABCD representing a binary number. Z should be 1 if the input is at least 5, but is no greater than 11. Use one OR gate (three inputs) and three AND gates (with no more than three inputs each). Submit a truth table and Boolean expressions and also submit a schematic of your final circuit generated from SimUaid.