Recap of Lecture 02 Generations of Computer Types of Computers Classifications of Computers.

Recap of Lecture 02Recap of Lecture 02 Generations of Computer Types of Computers Classifications of Computers

INTRODUCTION TO Computer INTRODUCTION TO Computer

Lecture No 3

Computer Hardware

Manual & Automatic Input Devices

Output Devices

Computer HardwareComputer Hardware Hardware are the electronic and mechanical

components of a computer systems. Physical components and which can be

touched, handle or seen physically. Despite the difference in performance among

the different kinds of computers, every digital computer is made up of four basic units, Input Unit (Input Devices are used to enter data into

the Computer) Out Put Unit (Out Devices are used to see the result of

Processed Data ) Central Processing Unit (CPU) Secondary Storage

Organization of ComputerOrganization of Computer

.

Main Memory&

CPU(Central Processing Unit)

InputUnits

OutputUnits

Auxiliary Storage

Input UnitInput UnitThe initial unit which provides communications

between the user and the computer is the input unit.

This unit describes a device used to transfer information into a computing system.

The devices used to give data or commands to computer are called Input devices.

Input & Output DevicesInput & Output Devices

Input DevicesInput DevicesData or information can be fed into

computer by using different peripherals i.e. types of input devices.

Two types of input devices◦ Manual Input Devices ◦ Automatic Input Devices

Manual Input DevicesManual Input Devices A manual input device requires a human hand to

control it…

Mouse

Keyboard

Scanner

Camera

Manual Input DevicesManual Input Devices

Tracker ball

Joystick

A manual input device requires a human hand to control it…

Manual Input DevicesManual Input Devices

Keyboard

The most common input device

You press keys to input data into the computer

The most common type of keyboard is the QWERTY keyboard

People are familiar with keyboards, so they don’t need to be trained

Skilled typists can work very quickly

They are very reliable and cheap

Many people cannot type and look at the screen at the same time, so typing can be time consuming

Uses Advantages DisadvantagesDevice

Manual Input DevicesManual Input Devices

Mouse

Most common pointing device

Used to point and click on icons or menus

Combines well with a keyboard

Fast and accurate

Need a flat surface to use them

Tracker ball

A tracker ball is basically an upside down ball mouse.

The user runs their thumb over the ball to control the on-screen pointer

Useful where desk space is limited

Some people find that the thumb gets painful with prolonged use

Ball can get greasy and dirty

Uses Advantages DisadvantagesDevice

Manual Input DevicesManual Input DevicesUses Advantages DisadvantagesDevice

Scanner

Used to convert printed images or text into a file of digital data

Images can be edited before use

The quality of the final image is dependent on the original image

Joystick Originally designed forpilots to control aeroplanes

Used to control wheelchairs and for playing games

They give a more realistic gaming experience when playing games such as flight simulators

Many different types available

Some people find them difficult to operate.

Manual Input DevicesManual Input Devices

Digital Camera

Used for taking still images which can be uploaded to a computer for permanent storage

You can preview the image before pressing the shutter button

No film needed or development costs

Unwanted images can be deleted

When the drive is full, images need to be uploaded to a computer or deleted

Touchpador Fingerpad

A pointing device, built into a laptop for convenience

Portable - built into the laptop

Small movements needed to move the cursor

Takes practice to master

Uses Advantages DisadvantagesDevice

Automatic Input DevicesAutomatic Input Devices

An automatic input device inputs data without the need for human intervention (once the device has been set up), e.g. MICR, OMR, barcode reader, webcam, microphone.

Microphone

Webcam

Barcode reader

Automatic Input DevicesAutomatic Input Devices

MICR

MagneticInk Character Recognition

Banks print important data on the bottom of cheques using magnetic ink

This ink is then read by a computer

Very quick and accurate processing of data – very low error rate.

Very secure as any attempt to change the numbers on a cheque will be ignored as the reader only recognises magnetic ink in the same font

Expensive to produce and print magnetic ink, and the reader is also expensive

Banks are the main user – very few other applications

Uses Advantages DisadvantagesDevice

Automatic Input DevicesAutomatic Input Devices

OMROpticalMarkRecognition

Used to mark multiple choice exam papers, National Testing Service (NTS) use OMR for paper checking .

Very fast method of reading data, which save time.

More accurate than humandata entry

Sometimes incomplete marks are not read correctly

Uses Advantages DisadvantagesDevice

Automatic Input DevicesAutomatic Input Devices

Barcode Readers

Used to identify products in shops

The code is read by a barcode scanner which identifies the product name, product size/weight manufacturer name

Very quick and accurate way to enter data – suits busy shops

Prices changes are made on the database, not the barcode

All barcodes need to be programmed into the computer in advance

Uses Advantages DisadvantagesDevice

Uses Advantages DisadvantagesDevice

Microphone Used to input sound into the computer

Used to give the computer commands, or to dictate letters directly to a word processor

Very cheap piece of equipment

Helpful for people with additional needs or for busy people who need very quick letters

Computer can misread voice instructions due to natural variations in people’s voices

Automatic Input DevicesAutomatic Input Devices

Webcam Used to input moving images into the computer for use in online communication

Very cheap piece of equipment

Enables people to see each other

The moving picture tends to flicker due to current limitations in data transfer

Output DevicesOutput Devices

Output DevicesOutput Devices An output device is used to display or use

information that comes out of a computer system.

Output devices convert electrical signals from a computer system into…

Sound (speakers or headphones) Images ,video & Text (screen or printer)

Output DevicesOutput Devices

Monitor Speakers

Plotter

Headphones

Printer

Output DevicesOutput Devices

TFT Monitor

Thin Film Transistor monitors are more commonly known as flat screens or LCD screens

Take up very little space

Run very quietly and produce little heat

Use about a third of the energy ofa CRT monitor

Easy to damage

Colour contrast on cheaper models is not as good as CRT monitors

Uses Advantages DisadvantagesDevice

CRT Monitor

Cathode Ray Tube is very old technology.Almost completely replaced by flat screen monitors

Reliable

Last for a very long time

Large

Can be heavy

Produce a lot of heat

Old technology

Output DevicesOutput Devices

Speakers& Headphones

When connected to a computer through a sound card, music can be played

Gives feedback to user during general computer use

Games are a lot more involving and realisticwith sound

Speakers are not useful in a network room, as everyone would disturb each other

Headphones can be uncomfortable with extended use

Uses Advantages DisadvantagesDevice

Plotter These are specialist printers that can produce high quality printoutson large piecesof paper

Very high quality printouts

Almost any size paper can be used

Slower than normal printers

Expensive

PrintersPrinters

There are 3 main types of printer…

Dot Matrix

Laser

Inkjet

Uses Advantages DisadvantagesDevice

General purposeuse for family orhome office

Cheap to buy

Latest modelscan be very fast

Ink cartridges can be very expensive

Business use for letters,stationery and images

Quality printing

Good for large areas of colour

Quiet & Quick

More expensive to buy than inkjets

Toner cartridges are expensive

Business usefor duplicatedocuments

Can make a carbon copyCan print on continuousrolls of paper

Noisy and rather old-fashioned technology

Poor quality and only prints in black ink

Soft copySoft copyThe result (text/graphics ) appear on displayed

screen are known as soft copy and will disappear if display is switched off.

Therefore this form of output is not permanent and can be removed, changed or corrected.

Output devices used for soft copy: Visual display unit (monitor or TV screen)

Hard copyHard copy The results (text/graphics) printed on paper is known as

Hard Copy. It is considered as permanent copy and can be retained

even computer is turned off. Output devices used for Hard copy:

◦ Printer◦ Plotters

SummarySummary

Introduction to Computer Hardware Input Unit ,Out Put Devices. Different Types of Manual & Automatic Input

Devices Out Put Devices Soft Copy Hard Copy