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LIS508 lecture 3:

computer & input devices

Thomas Krichel

2002-10-06

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Admin news

Grades for the quizzes will be madeavailable at

http://wotan.liu.edu/home/krichel/lis508w03a/grades/secret.html

where secret is your word, transliteratedinto all lowercase, example

seCret secret

SecrEt secret

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Literature

Peter Norton New inside the PC chapter

1 and 5

Ruth Maran and Paul Whitehead Teach

yourself computers visually, chapter 1

and 3

Hutchinson and Sawyer chapter 2

White, part 5

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Hardware and Software

Hardware is anything in the computer youcan touch.

Software are the instructions that makethe computer do things.

In early days, software was closely tied tohardware. It could only run on machines ofa specific hardware and was useless onother machines.

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structure

general things about computers

looking at computer hardware

bus input devices

keyboard

mouse other

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Computers

An old distinction is the following

A Mainframe is a computer that are used bymany people in an organization. They access

it through terminals.

A personal computer is a machine that isused by only one person at a time. In olden

days it could only do one thing at a time. A PC is a special type of personal

computer.

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What is a PC

The PC was first brought out by IBM in 1981

IBM published the design.

Processor chips supplied by Intel.

Software to run it was bought from Microsoft Microsoft had the right to have other companies use

the operating system.

A PC is any computer that basically follows this

tradition. Intel processor

Microsoft software

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Basic parts of a PC

Display do not open

Input no need to open Keyboard

Mouse etc System Unit may be opened

Logic system

Display system

Storage system Input output system

Communication system

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Opening the system unit

Voltages used in the PC are 3 to 12 V

Be aware of static electricity, touch firstunpainted part of case first

Keep power cable plugged in a groundedsocket

Never open sealed part of the powersupply

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Logic system I

Motherboard green plastic sheet

with traces and slots

usually complying to a standard called plugand play

Jumpers can set key features

Jumper wires stick out of the motherboard Can be shortened with jumpers

Do not change unless you have to

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The logic system II

CMOS or flash memory

Powered by battery

holds the Basic Input Output System (BIOS)

Central Processing Unit (CPU),recognizable through its fan

Cache memory for CPU

Main memory socket

The Bus (see later)

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BIOS

Is the software that makes the components ofthe PC work together

When the computer boots it tells you how to

enter setup There you can make changes to the BIOS

setting

The way that you do this is not standardized It usually is a simple menu.

Be careful

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Usual things to set in the BIOS

Set the hardware clock

Set processor speed setting

Tell the machine what disks you have Power management options

Automatic wake up

Boot sequence setting

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The Bus

Set of connections between devices in thesystem unit. Not very precisely defined

Types of bus

Industry Standard Architecture ISA bus (16bit), old

Peripheral Component Interconnect PCI bus

(32 bit) Accelerated graphics port (AGP) bus, only for

graphics

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The CPU

Quality of CPU is a major component ofthe speed of the machine

Speed of the CPU is measured in Hertz,

as the number of instructions per second. Intel are the main manufacturer

Pentium

Celeron Processor but other manufacturers may be offering

better quality/price.

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The components on the bus

The display system

Video card

Storage system

Hard disk

Floppy disk

CD-rom

CD-R

CD-RW

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Other components on the bus

Modems, allow communication over aphone line

Internal modems with own serial device

It squeaks

Network interfaces

network cards

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Input/Output components

Parallel port

Parallel because it can move a whole byte at a time

Mainly used for connection to a printer Nowadays it can handle bidirectional traffic

Serial port

One bit at a time -- Uses thin cable Slow -- inexpensive

Universal serial bus (USB) replaces those

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Universal Serial Bus (USB)

It is a new, rectangular port device

4 wires

2 for power

2 for communication

USB has a hub/slave technology

One USB line can connect to a hub

The hub has several outgoing lines, that connect toother devices

This is achieved by a complex set of software

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Keys on a keyboard

Typewriter keys

Function keys

Arrow keys

Editing keys

Numeric keypad

Alt and Control keys

Escape, windows key

Obsolete keys

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Scholes layout

Initial layout be Christopher Scholesaround 1860.

Early typewriters jammed when adjacentkeys were typed to fast.

Scholes design resulted from trying toavoid this occurrence.

This resulted in the famous qwertykeyboard.

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Dvorak keyboard

An efficient keyboard for the Englishlanguage, patented by August Dvorak,cousin of the composer.

Result of efforts to study typewritingbehavior.

Studies in the US Navy suggest that the

payback period would be 10 days fromlearning Dvorak.

From my own experience, doubtful.

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The mouse

There are two-button and three buttonmice.

Since MS uses two buttons, three buttonmice are a dying species.

The third (middle) button can be emulatedon two-button mice by pressing the leftand the right button at the same time.

Use of the mouse is best avoided!

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The two buttons

Primary button -- usually left

Secondary button usually right

Actions in Microsoft windows Left click

Right click

Left double click (time adjustable)

Left drag and drop

Right drag and drop

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Health risks

Keyboard and mouse usage can causeserious injury.

From my experience, they are often not bethe lone cause.

Others are

Stress

Bad posture

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other devices

Replacements for a mouse are

trackballs

touchpads

joysticks

Pen-based devices

vary with respect to text recognition

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text and code scanners

bar-code readers

magnetic ink character recognition such ason bank checks.

optical mark recognition

optical character recognition

more general form of reading characters outof handwriting or print

expensive and error-prone

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image scanners

most widely used digitization device

you can try to run OCR once you have theimage

resolution measured in dots per inch. dpi

more dpi: crisper image

fewer dpi: smaller file

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audio input

Microphone with speech recognitionsoftware This used to be mainly for those who can not

type But the quality has improved, and maybe we

will use it for more general input.

Other analog to digital sound converters sound cards

MIDI board

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Other devices

sensors

biometric devices

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http://openlib.org/home/krichel

Thank you for your attention!