Combinational Logic Digital Design Department of Software Development Faculty of Information Technology Islamic University of Gaza Dr. Rebhi Baraka

Basic Combinational Logic Circuits AND-OR LogicAND-OR Logic AND-OR-Invert LogicAND-OR-Invert Logic Exclusive-OR LogicExclusive-OR Logic

Basic Combinational Logic Circuits AND-OR LogicAND-OR Logic

Basic Combinational Logic Circuits AND-OR Invert LogicAND-OR Invert Logic

Basic Combinational Logic Circuits Exclusive-OR LogicExclusive-OR Logic

Basic Combinational Logic Circuits Exclusive-NOR LogicExclusive-NOR Logic

Implementing Combinational Logic Implementing Combinational Logic From Boolean expression to logic circuitFrom Boolean expression to logic circuit –Given a Boolean expression, create a logic circuit that implements that expression. From truth table to logic circuitFrom truth table to logic circuit –Given a truth table, create a logic circuit that implements that table.

Implementing Combinational Logic Implementing Combinational Logic From Boolean expression to logic circuitFrom Boolean expression to logic circuit Logic circuit for X = AB + CDE.

Implementing Combinational Logic Implementing Combinational Logic Implement the following Boolean expression:Implement the following Boolean expression:

Implementing Combinational Logic Implementing Combinational Logic From truth table to logic circuitFrom truth table to logic circuit –Given a truth table, create a logic circuit that implements that table. OutputInput XCBA A’BC AB’C’ The SOP expression obtained from the truth table is

Implementing Combinational Logic Implementing Combinational Logic From truth table to logic circuit (continued)From truth table to logic circuit (continued)

Implementing Combinational Logic Implementing Combinational Logic Example: Design a logic circuit to implement the operation specified in the truth tableExample: Design a logic circuit to implement the operation specified in the truth table OutputInput XCBA A’BC AB’C ABC’

Implementing Combinational Logic Implementing Combinational Logic Example: Design a logic circuit with 4 inputs that will only produce a 1 output when exactly 3 inputs are 1s.Example: Design a logic circuit with 4 inputs that will only produce a 1 output when exactly 3 inputs are 1s. The combinations in which there are exactly 3 1s are listed in the table with their product terms DCBA A’BCD AB’CD ABC’D ABCD’ X = A’BCD + AB’CD + ABC’D + ABCD’

The Universal Property of NAND and NOR Gates NAND and NOR gates are “universal” because they can be used to produce any of the other logic functions.

The Universal Property of NAND Gates

The Universal Property of NOR Gates

These slides are based on Digital Fundamentals 9 th ed. By Thomas Floyd