AN INTRODUCTION

TO

COMPUTERS

A machine that can be programmed to acceptdata (input), process it into usefulinformation (output), and store it away (insecondary storage devices) for safekeepingor later reuse

Process is directed by software but performedby the hardware

What is a Computer?

Who are the Users?

Any individual who

operates a computer to

accomplish a task either

at:

Home

Office

Business

etc

Users Examples

Data Entry Operator (DEO) – type data into a machine-

readable format

Computer Operator – monitor the computer

Computer Programmer – write, test, implement, and

maintain programs

Systems Analyst – plan and design computer systems

Network Administrator – oversees the network

Chief Information Officer (CIO) – department manager

who makes strategic decisions relating to the flow of

information in the organization

Q 1

Components of Computer

Hardware

Software

Hardware

Those components of a computer that has

physical existence and can be touched

Software

Set of instructions and commands

that directs the hardware to do a

required task and produce the desired

results also known as Program

Computer Characteristics

Speed

Reliability

Storage capability 1010001110100011 I T

Classifications of Computers

Use the computer that fits your needs

Based upon

Size

Speed

Cost

Portability

Number of simultaneous users supported

Available software

Typical use

Types of Computers

Super Computers

Mainframe Computer

Mini Computer

PC/ Desktop/ Micro Computer

Laptop Computer

Notebook Computer

etc

Computers Applications

Graphics

Education

Energy

Law Enforcement

Transportation

Money

Agriculture

Government

The Home

Health and Medicine

Robotics

Training and Paperwork

Computer System

Processor (CPU)

Memory

Peripheral equipment

Connected to the computer by a

cable

Input Devices

Output Devices

Storage Devices

Other

Input and Output

The User Connection

Q 1

Input

Users submit input data

Data is converted into electronic form

Input Devices

Keyboard

Mouse

Trackball

Touchpad

Pointing stick

Digital Cameras

Optical-mark readers

Bar-code readers

Scanners

etc

Output

Users get processed information

Types

Screen – soft copy

Printer – hard copy

Sound

Graphics

Monitor

Data that is entered appears on the screen

Screen is part of the monitor

Pixel and Resolution

Pixels (or picture element) - tiny dots that

compose a picture

Resolution - the number of pixels displayed

on the screen (the higher the resolution, the

closer together the dots)

Size - 14 / 17 / 19 / 21 inches etc.

Graphics Standards

SVGA (Super VGA)

Resolution – 800 x 600, 1024 x 768, 1280 x 1024, 1600 x 1200 pixels

16 million colors

XGA (Extended Graphics Array)

High resolution

Supports more colors

Printer

Produces information on paper

Orientation

Portrait

Landscape

Methods of printing

Impact

Non-impact

Impact Printers

Line printer

One line at a time

Dot-matrix printer

One character at a time

Line printer prints One line at a time

Line printer prints One line at a time

Line printer prints One line at a time

Dot-matrix printer: One character at a time

Dot-matrix printer: One character at a time

Dot-matrix printer: One character at a time

Example

Non-impact Printer

• Laser Printer

• Ink-jet Printer

Transfers images to paper

Prints one page at a time

600-1200 dpi – High quality

Speed

Personal laser printers: 8-10 ppm

Network laser printers: 35-50 ppm

High-volume laser printers: up to 1000 ppm

Black and white / color

Laser Printer

Ink-jet Printer

Spray ink at paper

Black and white / color

Excellent graphics

Good quality

Slower than laser

How to Choose a Printer?

Choose based upon:

Speed

Quality

Black and White vs Color

Price

Sound

Creates multimedia output

Multiple sound effects

Speakers are used

The Central Processing Unit

What Goes on Inside the Computer

Q 2

CD-ROM

CPU

Expansion slots

Floppy drive

Hard disk

Memory chip

Motherboard

Power supply

Inside the Computer

Back of the Computer

Cooling Fan

Power Supply

Keyboard Connector

Mouse Connector

Parallel Printer Port

Video Connector

Motherboard

Microprocessor chip

Memory chips

Connections to other parts of

the hardware

Additional chips may be

added – math coprocessor

Storage Devices

Hard Disk

Floppy Disk

CD-ROM Disk

DVD-ROM Disk

The CPU stands for Central Processing Unit

When circuits are built into a single silicon chip,the chip is referred to as a microprocessor.

The CPU

The CPU Function

CPU processes information and performs all the

necessary arithmetic calculations.

• The CPU is like the “brain” of the computer

The CPU Size

Chip size is ¼ x ¼ inch

Contains millions of transistors

Information comes in many forms

Computers store information in digital form

i.e. 0 and 1

Text

12 3Numbers SoundsPictures

Information

A bit (binary digit)

is the smallest unit of information

can have two values: 1 or 0

can represent numbers, codes,

or instructionsOn

Bit Basics

Bit, Nibble, Byte

BIT

Binary DigIT

On/off circuit

1 or 0

Nibble

4 bits

BYTE

8 bits

Store one alphanumeric character

Measuring Storage Capacity

Byte

Kilobyte (KB)

Megabytes (MB)

Gigabytes (GB)

Terabytes (TB)

= 8 bits

= 1 Thousand Bytes

= 1 Million Bytes

= 1 Billion Bytes

= 1 Trillion Bytes

Terms used to describe file size or memory size:

Memory

An area where data/ information are

stored

Types of Memory

Primary Memory

Secondary Memory

Registers

Q 2

Primary MemoryMany Names

Primary storage

Primary memory

Main storage

Internal storage

Main memory

Types of Main Memory

RAM

Random Access Memory

ROM

Read Only Memory

RAM (Random Access Memory):

is used to store program instructions and

data temporarily

unique addresses and data can be stored in

any location

will not remain if power goes off (volatile)

RAM

ROM (Read-Only Memory):

information is stored permanently on a chip.

contains startup instructions and other

permanent data.

Cannot be changed by the user

Nonvolatile

ROM

Other types of Primary Memory

PROM

EPROM

EEPROM

Cache Memory

etc

Secondary Storage

Long-term storage

Non-volatile

Secondary Storage Devices

Magnetic Disk

Hard disk (40, 60, 80 GB etc)

Zip Disks (250 MB)

Floppy Diskette (1.44 MB)

Optical Disks

CD-ROM (700 MB = 450 standard Floppy Disks)

CD-R (WORM: Write Once, Read More)

CD-RW (Read-Write More)

DVD-ROM (4.7 GB to 17 GB)

Compressed storage

Diskette – about 500 printed pages

Optical disk – about 500 books

Economy

Savings in physical storage costs

Savings in the speed and convenience of

storing and retrieving data

Secondary Storage Benefits

Data Compression

Why use? Squeeze big files onto small disks

Speed up data transfer of files

Techniques Remove all extra space characters

Substitutes a smaller data string for afrequently occurring set of characters

Software uses formula to determine how tocompress

Must be decompressed

Networking

and

Data Communication

Q 3

Network

Definition A system that uses communications equipment to

connect computers and share their resources.

Types

Local area network (LAN) – connects computers in

close proximity

Metropolitan area network (MAN) – connect

computers between buildings in the same geographic

area

Wide area network (WAN) – connects computers over

great distances

Data Communications

Send and receive information over

communications lines

Basic Components

Sending device

Communications link

Receiving device

Protocol

Modem

Modulate

Convert from digital to analog

Demodulate

Convert from analog to digital

Speeds up to 56,000 bps (56K)

Types of Modems

Direct-connect

External

Internal

PCMCIA

Personal Computer Memory Card International Association

Used in Notebook and Laptop computers

Network Media

Twisted pair cable

Coaxial cable

Fiber optic cable

Wireless

Network Topology

Physical layout

Star

Ring

Bus

Node – any device connected to the network, e.g.

Server

Computer

Printer

Other peripheral

Q 2

Star

Central hub

All messages routed through hub

Hub prevents collisions

Node failure – no effect on overall network

Hub failure – network fails

Ring

Travel around circular connection in one direction

Node looks at data as it passes

Addressed to me?

If not my address, Pass it on

No danger from collisions

Node failure – network fails

Bus

Single pathway

All nodes attached to single line

Collisions result in re-send

Node failure – no effect on overall network

NIC

Network Interface Card

Connects computer to the wiring in the

network

Handle

Sending

Receiving

Error checking