This document provides an introduction to digital systems and computer organization. It discusses key concepts such as digital vs. analog quantities and binary digits. Binary digits can take on logic levels of 0 and 1, represented by voltage levels. The document also covers basic logic operations like inversion, AND, and OR gates. Truth tables are introduced as a way to represent the output logic levels of logic gates based on different combinations of input levels.

1. Choman technical Institute
IT-Department
First Stage
Computer Organization and Logic Design
Lecture 1
Introduction to Digital Systems
Lecturer: Nergz Star Mohammed
Email: nsm170h@cs.soran.edu.iq

2. 1
Digital Concept
The term digital is derived from the Way computers perform operations, by
counting digits.
Digital technology is applied in a wide range of areas in addition to computers.
Such applications
television,
communications systems, radar, navigation and guidance systems,
military systems,
medical instrumentation.

3. Digital and Analog Quantities

4. Digital and Analog Quantities
Types of electronic devices or instruments:
Analog
Digital
Combination analog and digital
Analog
 An Analog Electronic System
Public Address System used to amplify sound so that it can be heard by large
audience.

6. Digital
 A computer performs operations Digitally.
Analog and Digital
 A System Using Digital and Analog Methods

7. Binary Digits
The conventional numbering system uses ten digits:
0,1,2,3,4,5,6,7,8, and 9.
The binary numbering system uses just two digits: 0 and 1.

8. Binary Digits
 The two binary digits are designated 0 and 1
 They can also be called LOW and HIGH, where LOW = 0 and HIGH = 1

9. Binary Digits v.s. Logic Levels
Binary values are also represented by voltage levels
Logic Levels
Major parts of a digital pulse

10.  Base line
 Amplitude
 Rise time (tr)
 Pulse width (tw)
 Fall time (tf)
Logic Levels
tw = pulse width
 T = period of the waveform
 f = frequency of the waveform

11. Duty Cycle of a Binary Waveform

12. The duty cycle off a binary waveform ibis defined as:

13. Basic Logic Operations

14. Not Operation [Inverter]
When the input is LOW, the output is HIGH
When the input is HIGH, the output is LOW
The output logic level is always opposite the input logic level.
AND Operation
When any input is LOW, the output is LOW

15. When both inputs are HIGH, the output is HIGH
OR Operation
When any input is HIGH, the output is HIGH
When both inputs are LOW, the output is LOW

17. Truth Table