ch1_l1 ( computer system )

8/6/2019 CH1_L1 ( computer system )

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TOPIC 1.0

COMPUTER SYSTEM



WHAT IS COMPUTER??

� A programmable machine.

� The two principal characteristics of a computer are:

1) It responds to a specific set of instructions

in a well-defined manner.

2) It can execute a prerecorded list of instructions (a program).



COMPUTER¶S BASIC PROCESS

INPUT PROCESS OUTPUT

Keyboard

Microphone

Mouse

Scanner

System Unit

Monitor

Printer

Speaker



1.1 THE EVOLUTION OF COMPUTER

� First Generation (1939-1954) - Vacuum tube

� Second Generation Computers (1954-1959) - Transistor

� Third Generation Computers (1959-1971) ± IntegratedCircuit

� Fourth Generation (1971-1991) - Microprocessor

� Fifth Generation (1991 and Beyond)




� First Generation (1939-1954) - Vacuum tube

Atanasoff-Berry Computer 1939 UNIVAC 1951




� Second Generation Computers (1954-1959) - Transistor

Regency transistor radio

1954Philco and Emerson

transistor radios




� Third Generation Computers (1959-1971) ± Integrated

Circuit

Polaroid IC 1961 IC, from Smithsonian NMAH




� Fourth Generation (1971-1991) - Microprocessor

Intel 4004

microprocessor in 1971

IBM 5151 personal computer 1981

Apple II personal

computer 1978




� Fifth Generation (1991 and Beyond)

Nokia 9210

Communicator is

part of the latest

wave of web cellphones Wearable computers

Apple G4



1.2 PARTS OF COMPUTER

� Parts of computer:

Hardware - physical parts, which we can see

and touchExample:

Software - the instructions, or programs,

that tell the hardware what to do

Example:




(Hardware)




(Hardware)

Modem

-To connect computer to the Internet

- A modem is a device that sends and receives computer

information over a telephone line or high-speed cable




(Hardware)

System Unit - The core of a computer system

-The most important of these

components is:

the central processing unit ( CPU), or

microprocessor - acts as the "brain"

of your computer.

random access memory ( RAM) -temporarily stores information that

the CPU uses while the computer is

on.




(Hardware)

Components of System Unit




(Hardware)

System Unit (con¶t)

Main components of CPU:

1) Control Unit- extract information which is stored in the memory and

to decode and execute those instructions

2) ALU (Arithmetic Logic Unit)

± do the calculation and data comparison based on

instructions from control unit Arithmetic : mathematical operation (+,-,*,/)

Logic: comparison operation (= , < , > , <>, <= and >= )

3) Main Storage




(Hardware)

Mouse

- Used to point to and select items on your computer screen

- Usually has two buttons: a primary button (usually the left

button) and a secondary button.

- Many mouse also have a wheel between the two buttons,

which allows you to scroll smoothly through screens of

information.




(Hardware)

Speaker

- Used to play sound

- They may be built into thesystem unit or connected with

cables

-Speakers allow you to listen tomusic and hear sound effects from

your computer.




(Hardware)

Printer

- Transfers data from a computer onto paper

Inkjet printer (left); laser printer (right)

-Two main types of printers:

i) inkjet printers

� most popular printers for the home� can print in black and white or in full color and can produce high-quality

photographs when used with special paper

ii) laser printers

� faster and generally better able to handle heavy use.




(Hardware)

Keyboard

- Used mainly for typing text into your computer.

- It has keys for letters and numbers, but it also has special keys:

�

The f unction keys, found on the top row, perform different functions

depending on where they are used.

�The numeric keypad , located on the right side of most keyboards,

allows you to enter numbers quickly.

�The navigation keys, such as the arrow keys, allow you to move your

position within a document or webpage.



ComputerApplication

Software

Examples:


(Software)

Operating SystemSoftware

Examples:

y DOS

(Disc Operating System)y LINUX

y Windows

y Macintosh (³the Mac´)

Software




(Software)



STANDALONE

v/s

NETWORKED COMPUTER

STANDALONE COMPUTER NETWORKED COMPUTER

- Able to operate on their own

without a server.

-Information (files and programs)

is stored on the computer¶s hard

drive.

-Stand Alone Computers are

usually connected to their own

printer.

-Joined together by cables and are

connected to a server.

- The server stores information

(both files and programs) and

sends it out to the computers on

the network.

- A network usually includes a

printer that also is connected by

cables.



TYPES OF NETWORK

LAN

(Local Area Network)

MAN

(Metropolitan Area

Network)

WAN

(Wide Area Network)

- short distance

- office building,

school, or home

- typically owned,

controlled, and

managed by a single

person or organization

- physical area larger

than a LAN but smaller than a WAN, such as a

city.

- A MAN is typically

owned an operated by

a single entity such asa government body or

large corporation

- large physical

distance

- Most WANs (like the

Internet) are not owned

by any one

organization but rather

exist under collectiveor distributed

ownership and

management



TYPES OF NETWORK

(LAN)

Advantages of LAN:

�Files can be stored on a central computer (the file server)

allowing data to be shared throughout an organisation.

�Files can be backed up more easily when they are all on a

central fileserver rather than when they are scattered across a

number of independent workstations.

�Networks also allow security to be established, ensuring thatthe network users may only have access to certain files and

applications.

�Software and resources can be centrally managed.



TYPES OF NETWORK

(LAN)

Disadvantages of LAN:

�Limited :

- limited range or distance

- limited number computers that can be attached to asingle LAN

�Can be expensive.



ASSIGNMENT 1

QUESTION 1:

Distinguish between the functions of Operating System Software

and Computer Application Software

QUESTION 2:

Make comparisons between Windows and Linux.

REFERENCES<< minimum 2 references >>

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