Lecture of Computer

8/8/2019 Lecture of Computer

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What Is A Computer?

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y A computer is an electronic device, operating under the

control of instructions (software) stored in its own memory

unit, that can accept data (input), manipulate data (process),

and produce information (output) from the processing.

Generally, the term is used to describe a collection of devices

that function together as a system.


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What Is A Computer?

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y A computer is a programmable machine that receives

input, stores and manipulates data, and provides output in a

useful format.

y

takes input.. processes it according to storedinstructions produces results as output.


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Devices that comprise a computer system

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Printer

(output)

Monitor

(output)Speaker

(output)

Scanner

(input)

Mouse

(input)

Keyboard

(input)

System unit

(processor, memory)

Storage devices

(CD-RW, Floppy, Hard

disk, zip,)


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What Does A Computer Do?

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y Computers can perform four general operations,

Input

Process

Output Storage


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What Are The Primary Components Of

A Computer ?

y Input devices.

y Central Processing Unit.

y Memory.

y Output devices.

y Storage devices.

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Binary Numbers

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THE LANGUAGE OF COMPUTERS


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Binary Numbers

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Binary language consists of combinations of 1's and 0's that represent

characters of other languages (in our case the English language).

For example: 101 is a byte that represents an integer 5; each 1 or 0 is a bit.)

Units: 1 bit

8 bits = 1 byte

1kbyte = 210 = 1024 bytes

1Mbyte = 220= 1048576 bytes


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Hardware

The physical (electronic and mechanical) parts of

a computer.

Software The programs that control the operation of the

Computer


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Uses for a PC

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y Word Processing

y Database Management

y Spreadsheets

y Communication

y Finance

y Education

y Entertainment

y News and Information


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Input Devices

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yKeyboard.

yMouse.

yTouch ScreensyPens


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The Central processing Unit

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y The central processing unit (CPU) contains electronic circuits that

cause processing to occur. The CPU interprets instructions to the

computer, performs the logical and arithmetic processing

operations, and causes the input and output operations to occur. It

is considered the brain of the computer.


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The Central processing Unit

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y Its speed is measured in Megahertz (MHZ) (Millions of

cycles per second) or Gigahertz (GHZ) Billions of cycles per

second.


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Memory

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y Memory also called Random Access Memory or RAM

(temporary memory/ Non-volatile) is the main memory of the

computer. It consists of electronic components that store data

including numbers, letters of the alphabet, graphics and sound.

Any information stored in RAM is lost when the computer isturned off.

y Read Only Memory or ROM (Volatile memory) is memory that is

etched on a chip that has start-up directions for your computer. Itis permanent memory.


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Output Devices

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y Output devices make the information resulting from the

processing available for use. The two output devices more

commonly used are the printer and the computer screen.

y The printer produces a hard copy of your output, and the

computer screen produces a soft copy of your output.


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Storage Devices

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y secondary storage devices are used to store data when they are not

being used in memory. The most common types of auxiliary

storage used on personal computers are floppy disks, hard

disks and CD-ROM drives.


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Operating System Software

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y Operating system software tells the computer how to perform the

functions of loading, storing and executing an application and how

to transfer data.

y Operating System is the software that manages the overall

operation of the computer system.

y Main purpose is to support application programs..

y Hide details of devices from application programs..


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Application Software

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y Application Software consists of programs that tell a computer

how to produce information. Some of the more commonly used

packages are:

Word processing

Electronic spreadsheet

Database


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Classification of Computers

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ySupercomputersy The largest, most powerful, and most expensive

y Used by universities, research institutions, large corporations,

and the military


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yMainframe Computersy Less powerful and less expensive than supercomputers

y Used by businesses with large amounts of data that need to be

stored in a central computer


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yMinicomputer

yOften used as the host computer in a network

of smaller computers

yPriced in the tens of thousands to a few

hundred thousand dollars

yManufacturers:Compaq (VAX), IBM

(AS/400), and Hewlett-Packard


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yServers

ydesigned to support a computer network that

allows you to share files, application software,

hardware, such as printers and other network

resources.

yExample: file server, printer server, database

server,


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Server computers usually have following characteristics:

Designed to be connected to one or more networks

The most powerful CPUs available

Multiple CPUs to share the processing tasks

Large memory and disk storage

High-speed communications capabilities


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yPersonal Computers / Clients The most common for home users , computers that can fit

on a desktop or in one's briefcase.

Can perform all of its input, processing, output and storageactivities by itself.


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Importance of Standards

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yCompatibility

y Software and peripheral devices from one computer can be

used with another computer.

y In a networked environment, computers need to communicate

to share databases and other computing resources.

y In addition to power and cost, compatibility is an extremely

important factor in purchasing decisions.

Documents

Lecture of Computer