This document provides an overview of computers including: 1. It defines a computer as an electronic device that processes input data to produce output. 2. It discusses the characteristics, history from mechanical to electronic computers, generations, and classifications of computers. 3. It describes the main components of a computer system including hardware components like the CPU, memory, storage, input/output devices and software components like operating systems, applications, and programming languages.

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Computer Science
1

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Contents:
1. Introduction
2. Characteristics of Computer
3. History of Computer
4. Generation of Computer
5. Classification of Computer
6. Computer Components

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Introduction
What is a Computer?
Electronic device that processes the input
data to give desired results as output.
Input Process Output

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Characteristics of Computer
▪ Speed: Instructions per second measured by :
ms, µs, ns, and ps.
▪ Accuracy: 100%
▪ Huge Storage Capability: measured by KB, MB, GB, TB
▪ Versatility: ability to process any kind of data to perform
different tasks: play, music, letter, …etc.
▪ Reliability: 100% accurate.
▪ Diligence: ability to perform repeated operation efficiently
without get tired.
▪ Networking: interconnected in to a netwo

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Electronic Computer Devices
Electro-mechanical Computing
Devices
Mechanical Computing Devices
• Manual Computer Devices
• Semi Automatic Computer Devices
History of Computer

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▪ EDSAC (Electronic Delay Storage
Automatic Calculator) by M.
Wilkes: 1949
▪ EDVAC ( Electronic Discrete
ENIAC EDSAC
History of Computer(Cont.)
Electronic Era:
▪ ENIAC ( Electronic Numerical
Integrator And Calculator) by John
W. Mauchly and J.P. Eckert: 1947
Variable Automatic Calculator) by
Von Neuman
▪ UNIVAC I (Universal Automatic
Computer) by Mauchly and J.P.
Eckert :1951 UNIVAC I EDV

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Digital Computer
Analog Computer
According to the computer Working Principle:
1. Analog Computer: measuring continuous
type of input data. like; current, voltage etc.
2. Digital Computer: counting discrete type of
input data (digits). Like; number, letter etc.
3. Hybrid Computer: combines the features of
Analog and Digital computers. Used in
Hospital, scientific research etc.
Classification of Computer

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Classification of Computer(Cont.)
According to the purpose of use:
1. Special Purpose Computer: doing particular task or
application. (Hybrid computer).
2. General Purpose Computer: doing different tasks or
different applications. (Digital computer).

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Desktop
Laptop
Classification of Computer(Cont.)
According to the Computer Size:
1. Micro Computer: desktop, laptop, notebook
(education, graphical design, etc.). 2. Mini
Computer (data processing programing,
business, etc.). 3. Mainframe Computer
(telecom companies, large-scale data
processing, etc.). 4. Super Computer (weather
forecasting, space research

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Microcomputers:
Desktop and Portable
▪ Desktop (PC)
▪ Laptop (Notebook)
▪ Netbook
▪ Tablet
▪ PDA (Personal Digital Assistant)
or Handheld Tablet Netbook
▪ Smart Phone
Smart Phone
PDA

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Computer Components
Computer System consists of three Components :
Computer System
Hardware Software Human ware
All
physical
Programs User

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Computer Components (Cont.)
First: Hardware components consist of:
Input Devices Output Devices
Internal Devices Peripherals Devices
Hardware
Secondary
Storage Devices
ALU CU
Main Store Unite
Central Processing Unite

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Hardware
Components
Central Processing Unit (CPU): It is the main unit inside the
computer that executes instructions to do arithmetic and
logical operations to process the input data and control all
events inside the computer.

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Input Unite Output Unite
CPU
Arithmetic
Logic Unite
ALU)
(
Control
Unite (CU)
Main Memory
Secondary Memory
Storage
Devises
• CPU: measured in
Megahertz (MHz )
andGigahertz (GHz).
• Most popular CPU are:
Intel and AMD.

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Hardware Components (Cont.)
Input Unit: It is the unit that
entered the data in to a computer
from the Input Devices:
1. Keyboard
2. Mouse
3. Light Pen
4. Trackball
5. Joystick
6. Tag Reader
Keyboard
Trackball Light Pen
Tag Reader
Joystick
Digital Cameras
Mouse

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MICR POS Terminal
11. Graphic Tablet
12.Vision Systems
13.Scanners
▪ Barcode Reader
7. Digital Cameras
Hardware Components (Cont.)
8. Point Of Sale Terminal (POS Terminal)
9. Magnetic Ink Character Recognition(MICR)
10.Voice Recognition Systems
▪ Optical Mark Reader (OMR)
▪ Optical Characters Reader (OCR)
VRS Barcode Reader

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OCR
Hardware Components (Cont.)
Output Unit: It is the unit that gives the results of processed
data as an output from a computer by using the Output
Devices :
Graphic Tablet
OMR

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1. Monitors:
Cathode Ray Tube (CRT)
Liquid Crystal Display (LCD)
Light Emitting Diodes (LED)
2. Speakers
3. Printers
4. Plotters
Monitor
Plotters s
Hardware Components (Cont.)
Storage Devices: and
Speakers
Printe
r

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Hardware Components (Cont.)
RAM
Random Access Memory
Volatile, Read/Write
ROM
Read Only Memory
Non-Volatile, Read Only
Main Memory
ROM
RAM

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Floppy Disks Hard and Sold Drives
Pen Drive DVD
COM
External Hard Disk Memory Cards
Magnetic Tape
Secondary Memory
 Magnetic Disks:
▪ Hard disks ( 500 GB, 1TB)
▪ Floppy disks (MB1.44 MB and
2.88)  Magnetic Tape (185
GB)  Optical Storage:
▪ CD-ROM, CD-R, CD-RW (700
MB)
▪ DVD-ROM, DVD-R, DVD-RW,
and DVD-RAM (4.7 GB)
CD: Compact Disk
DVD: Digital Versatile Disk
 Pen Drive
 Memory Cards
 External Hard Disk

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 Computer Output Microfilm and Computer
Output Microfiche

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Hardware Components (Cont.)
Storage Devices:
Measured by:
Bit, Byte
Bit = 0 or 1
byte = 8 bits
bit
Byte= 8 bits
KB= 1024 byte
MB= 1024 Kilobyte
GB= 1024 Megabyte
TB= 1024 Gigabyte

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Computer Components (Cont.)
Second: Software components consist of:

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Package Software Custom Software
System Software Application Software
Software
Programming Language &
Scripting
Operating
System
Utility
Software

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Software
Components
Software: set of instruction in the form of programs that used to operate
the computer and related devices. Types of Software:
1. System Software:
-Operating System Software: DOS, Windows XP,
Unix etc.
-Utility Software: Anti Virus Utility, WinRAR, Operating Systems
Disk Clean,
Back Up etc.
2. Application Software:
-Package Software: Ms. Office 2013, Photoshop etc.

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-Custom Software: Bespoke Software that
especially developed for specific organization
like; SAGE(Accounting).
3. Programming Language & Scripting:
Assembly, FORTRAN etc.
Applications and Utility Software