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Polly Huang, NTU EE Hardware 1

Introduction to Computer Science

Polly Huang

NTU EEhttp://cc.ee.ntu.edu.tw/~phuang

phuang@cc.ee.ntu.edu.tw

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Inside Your PC

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Todays Computer

Real Life View

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Inside Your PC

Input/Output

On the Inside

Storage

Processing

Other parts not on standard teachingmaterial

Looking into the Future

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Todays Computer

Real Life View

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Input devices

Accept data or commands and convertthem to electronic form

Getting data into the computer

Typing on a keyboard

Pointing with a mouse

Scanning with a scanner or bar-code reader

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Keyboard

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Types of Keyboard

101-key Enhanced keyboard

104-key Windows keyboard

3 more keys?

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Types of Keys

Typing, numeric, function, and controlkeys

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QWERTY Layout

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A Legacy Technology

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Slower is Better

The mechanical typewriter

Key attached to the typebar

Typebar tip molded with the corresponding letter

So striking the key will rest the typebar on thepaper, and therefore leave a print of the letter

The design consideration

If typed too fast, typebars jam

To SLOW DOWN the speed, spread the often-typed letters apart in the layout

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But computer keyboards areno longer mechanical.

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There Are Alternatives

Dvorak Layout

To minimize the amount of fingermovement

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Its not a perfect world.

Pollys Law:

Consumers takes the cheap andgood-enough option

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A Computer Itself

MicroprocessorKey Matrix

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Circuit Underneath A Key

Constant

current

Constant

current

Press the Key

Detect

current

Microprocessor

The position on

the key matrix

(16 bytes)

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To the PC

PS/2 Connector

PCKeyboard

The position on

the key matrix

(16 bytes)

Power

(5 Volt)

Keyboard

Controller

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Mouse

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>

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Polly Huang, NTU EE Hardware 21

A Natural Interface

Now, think back when you are a baby

You saw theres some nice apple juice inyour bottle right on the desk

What do you do to let your mom knowyou want that bottle?

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Moms Are Great

Computers are stupider than the moms

They only start to know what people mean bypointing in about late 1970s

Macintosh APPLE IIs evolve first

Windows 3.1 comes later for IBM PCs

GUI (Graphical User Interface)

This explains why would anyone use commandline at all

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Types of Mouse Mechanical

Use rollers to trackmotion

Track ball

Optical

Use a tiny camera totracking the motion

LED (red lightbeamer)

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Mechanical Mouse

Two Rollers

One vertical

One horizontal

Rolled by thetrack ball

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Spinning Disk Each roller connects

to a shaft

The shaft spins adisk

The disk has 36

holes around theouter edge

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Pulses of Light

A pair of infra-redLED and sensor oneither side of the

disk LED beams infra-red

light

The holes break thebeam of light as thedisk spins

Sensor receivespulses of light

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The Mouse Guts

The microprocessordetects

The number ofpulses

3 bytes

Send the datathrough

PS/2 connector

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Optical Mouse

A tiny camera

1,500 pictures everysecond

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Taking the Pictures Red LED beams

Mouse pad bouncesback the light

CMOS senses theimage from thebounced light

CMOS >