IS 2101---Fall 2009

Chapter 2: Hardware1/14/2010

Objectives

•What exactly is a computer, and what are its four main functions?•What is the difference between data and information?

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Objectives

•What are bits and bytes, and how are they measured?•What devices do you use to get data into the computer?

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Objectives

•What devices do you use to get information out of the computer?•What’s on the front of your system unit?

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Objectives

•What’s on the back of your system unit?•What’s inside your system unit?

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Objectives

• How do you set up your computer to avoid strain and injury?

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Data Processing

• Input• Process• Output• Store

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Information vs. Data

• Information is organized– Phone book

• Information is more valuable than data

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Bits and Bytes

• Representing information– Electrical flow: on or off– A bit has two possible values– Put bits together to represent more

complex information (alphabet of two letters)

• Measuring information

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Input Hardware

• Text input: keyboard• Pointer input: mouse and stylus• Sound: microphones• Light: cameras• Measurements: thermometer

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Connecting

• Wire connections• Wireless– Infrared (line of sight)– Radio (subject to interference)

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Keyboards

• Variety of arrangements–Major: QWERTY vs. Dvorak–Minor: specialized keys and function

keys– Numeric pads– Special functions

• Special characters: beyond English

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Pointers

• Detecting motion–Mechanical– Optical (not good on clear glass)

• Buttons• Scroll wheel• Joysticks• Trackballs• Touchpads1/19/2010 IS 2101/07---Spring 2010 14

Everything’s Customizable

• What each button on a keyboard or mouse does can be customized

• You probably wouldn’t want to change most of them

• Utilities are provided to map various extra buttons to different functions

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Output Devices

• Video: Monitor, projector• Printer• Speakers• Motors

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Monitors

• Pixels– Resolution– Color depth• RGB

• Aspect ratio

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Printers

• Technology– Impact– Inkjet– Laser

• Quality• Cost• Speed

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System Unit

• Power• Processor• Memory• Storage• Peripheral connectors

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Processor

• Central Processing Unit• Directs the operations of the

computer and carries out computations

• Computers generally have several special purpose processors as well, such as for graphics– These may be more powerful than the

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Processor Design

• Different processors operate differently

• Programs for computers usually have to be designed for a particular process– And for other characteristics we’ll talk

about later

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Processor Characteristics

• Number of cores• Clock speed• Data width and bus width

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Heat

• Computers use a great deal of energy when running

• Almost the only output for that energy is heat– Very few moving parts

• Computers can overheat and damage themselves without adequate cooling

• The CPU is particularly vulnerable

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Memory

• Used by the computer to store data and programs in active use

• Fast, relatively expensive, volatile• Usually called RAM (Random Access

Memory)

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Price changes

• My first computer: 16 K memory was $300

• Today: 2 G memory is $100• In price per Meg:– Old: $19,200– New: $0.10

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System Unit

• Main board• Extension cards plug in to main

board• Memory plugs into main board

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Storage

• Relatively cheap• Slower• Large volume• Not volatile• Read-only vs. Read-write

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Storage Technology

• Generally, data stored on disks in concentric circles

• Terminology– Platters, tracks, cylinders

• Read/Write heads• Speed– Rotation speed– Seek speed– Data transfer speed

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Connectors

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Connectors

• Video• Mouse and Keyboard• USB• Parallel• Serial• Firewire• Ethernet

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Ergonomics

• Chair height• Monitor height• Wrist support• Repetitive stress• Hearing damage

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