ITM207 CHAPTER 4 NOTES | COMPUTERS AND ELECTRICITY | COMPREHENSIVE TERMS & CORRECT DEFINATIONS 2025

ITM207 Chapter 4 Notes

Computers and Electricity

Gate:
A device that performs a basic operation on electrical signals

Circuits
Gates combined to perform more complicated tasks

We describe the behavior of gates and circuits through 3 ways

Boolean Expressions
●​ Uses Boolean algebra, a mathematical notation for expressing two-valued logic

Logic Diagrams
●​ A graphical representation of a circuit; each gates has it’s own symbol

Truth Tables
●​ A table showing all possible input values and the associated output values


Gates
6 Types of Gates:
●​ NOT
●​ AND
●​ OR
●​ XOR
●​ NAND
●​ NOR

Typically, logic diagrams are black with gates being told apart by their shape only

NOT Gate

A NOT gate accepts one input signal (0 or 1) and returns the opposite signal as output

,AND Gate

An AND gate accepts two input signals
​ If both inputs are 1: output = 1
​ Otherwise input is 0




OR Gate

An OR gate accepts two input signals
​ If both inputs are 0: output = 0
​ Otherwise output is 1

, XOR Gate
An XOR gate accepts two input signals
●​ If both inputs are the same output is 0
●​ Otherwise output is 1
●​ The difference between XOR gate and the OR gate is in one input situation
●​ (When both inputs are 1, the OR gate products a 1 and the XOR produces a 0)
●​ XOR output is 1 if (and only if):
●​ Either one input or the other is 1 and this is excluding the case that they both are




NAND Gate

The NAND (“NOT of AND”) gate accepts two input signals
●​ If both are 1, the output is 0
●​ Otherwise the output is 1