Enhanced A+ Guide to Managing and

Maintaining Your PC Third Edition

Chapter 1

How Computers Work

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You Will Learn…

About the functions performed by different hardware components of a microcomputer

About the three kinds of software and how they relate to one another and to hardware

How the CPU uses primary and secondary storage to manage software

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Hardware and Software

Hardware• Physical components of the computer

MonitorKeyboardMemory chipsHard drive

Software• Set of instructions that directs the

hardware to accomplish a task

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Chauffer Analogy

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Functions of Hardware

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Binary Number System

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Hardware

Central processing unit• Most important hardware device• Receives input and sends output• Stores data and instructions; performs calculations

Requirements of hardware devices• Method for CPU to communicate with the device• Software to instruct and control the device• Electricity to power the device

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Hardware Used for Input and Output

Ports• Physical connectors that allow a cable from a

peripheral device to be attached Input devices

• Keyboard• Mouse

Output devices• Monitor• Printer

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Ports

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Input Devices

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Output Devices

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Hardware Inside the Computer Case

System board Permanent storage

• Floppy drive• Hard drive• CD-ROM drive

Power supply Circuit boards

• CMOS (most CPUs)• TTL

Cables

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Hardware Inside the Computer Case

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CMOS Chips

Require less electricity Hold data longer after electricity is

turned off Are slower Produce less heat

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The System Board

Largest and most important circuit board

Contains the CPU

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The System Board

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Major Components of System Boards

For processing• CPU• Chip set that supports CPU by controlling

many system board activities For temporary storage

• RAM• Cache memory

continued

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Major Components of System Boards

Allow CPU to communicate with other devices• BUS• Expansion slots

Firmware and setup information• Flash BIOS memory chip• CMOS configuration chip

Electrical system• Power supply connections

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Components Used Primarily for Processing

CPU or microprocessor• Executes most computer processes

Chip set• Relieves CPU of some processing• Provides careful timing of activities to increase

overall speed Coprocessor

• Supports and enhances function of some older CPUs (pre-1995)

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The CPU

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Temporary (Primary) Storage Devices

Used by the CPU to process data and instructions

Provided by RAM (random access memory devices)• SIMMS (single inline memory modules)• DIMMS (dual inline memory modules)

Cache memory

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SIMMS and DIMMS

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Cache Memory

For new CPUs• Stored inside CPU housing on a memory

chip that sits close to the CPU microchip For older CPUs

• Stored on the system board either in individual chips or on memory modules called COAST (cache on a stick)

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Cache Memory

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Permanent (Secondary) Storage Devices

Remote to the CPU Permanently hold data, even when PC

is turned off Most popular devices:

• Hard disks• Floppy disks• Zip drives• CD-ROMs

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Hard Drives