Introduction To Computer 1 Source by Bryan Pfaffanberger & Bill Daley.

Introduction To Computer 11

Source by Bryan Pfaffanberger & Bill Daley

AWAS…..Copyright © 2003 Prentice Copyright © 2003 Prentice Hall, IncHall, Inc

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DILARANG KERAS

Understanding the Computer

A computer is a machine that, under a program’s direction, performs four basic operations: input, processing, output, and storage.

A program is a list of instructions that tells a computer how perform the four operations.

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Input

The first operation. The computer performs arithmetic or comparison operations on data. Electrical impulses representing words, numbers, images, or sounds.

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Input Input is any data entered into the computer’s memory.

Types of input include:

Data– Unorganized information (words, numbers, images, or sounds) that the computer converts to meaningful information.

Software– Programs transferred from storage devices to the computer’s memory.

Commands– Instructions that tell the computer what to do.

Responses– Prompts requiring user feedback.

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Input Devices: Giving Commands

Input devices are types of hardware that enable you to get programs, data, commands, and responses into the computer’s memory.

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Digital Cameras

Microphone

Touch Screen

Keyboard & Mouse

Wand ReaderStylus Pen

Keyboard

The keyboard allows the computer user to enter words, numbers, punctuation, symbols, and special function commands into the computer’s memory.

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Types of Keyboards

Enhanced or Extended keyboard– Typically 101 keys laid out in the QWERTY fashion; connected to the computer by a serial cable.

Cordless keyboard– Uses infrared or radio wave signals.

Ergonomic keyboard– Designed to help prevent cumulative trauma disorder (CTD) or damage to nerve tissues in the wrist and hand due to repeated motion.

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Enhanced / Extended Keyboard Ergonomic Keyboard

Input Devices 99

Keyboard Mouse– pointing device

Microphone–speech-recognition

Digital Cameras

Pointing Devices

Pointing devices enable the user to control the movements of an on-screen pointer.

They enable the user to initiate commands and to respond to the active program.

They are used to provide input in graphics programs.

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Types of Mice

PS/2– Most commonly used; connects to PS/2 port or USB port.

Serial– Not commonly used; connects to a serial port.

Bus– Obsolete; connects to an expansion card.

Cordless– Uses infrared signals; must be within sight of the receiving port.

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PS/2 Mouse Cordless Mouse

How a Mouse Works Mouse buttons enable the user to initiate actions.

Clicking (left-, right-, or double-clicking) allows the user to select an item on the screen or open a program or dialog box.

Click and drag– Holding down the left mouse button and moving the mouse enables the user to move objects on the screen.

A mechanical mouse uses a rotating ball to position the pointer on the screen.

An optical mouse uses laser light to determine the pointer position.

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Other Types of Pointing Devices 1313

Foot Mouse

JoystickTouch Pad

Touch Screen

Trackball

Pointing Stick

Pen

Speech Recognition

Speech recognition is a type of input in which the computer recognizes words spoken into a microphone.

Special software and a microphone are required.

Latest technology uses continuous speech recognition where the user does not have to pause between words.

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Optical Input Devices 1515

Digital Cameras

Digital Video

VideoconferencingWeb Cams

Click on the picture to play video

Other Input Devices 1616

Scanners

Flatbed Handheld

Fax Machines

Processing

The second operation.

The computer performs arithmetic or comparison (logical) operations on the data.

Performed at a very high speed.

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Arithmetic

4 + 16 = 20

Logic

728 > 546

Output

The third operation.

The computer shows the results of the processing operation in a way people can understand.

Data is processed into information.

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Output Devices

Output devices are peripheral devices that enable us to view or hear the computer’s processed data.

Visual output– Text, graphics, and video.

Audio output– Sounds, music, and synthesized speech.

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Visual Display System

A visual display system is composed of two parts:

Video adapter– Responsible for video quality.

Monitor– Displays the video adapter’s output.

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Monitor

A monitor is a peripheral device which displays computer output on a screen.

Screen output is referred to as a soft copy.

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Types of Monitors Cathode-ray tube (CRT)– Resemble televisions; use picture tube

technology; inexpensive, but they take up desk space and use a lot of energy.

Liquid Crystal Display (LCD or flat-panel)– Cells sandwiched between two transparent layers form images; used for notebook computers, PDAs, cellular phones, and personal computers; expensive, and they take up less desk space and use less energy than CRT monitors.

Types of LCD monitors:

Passive-matrix LCD

Active-matrix LCD

Gas plasma display

Field emission displays

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CRT LCD

Monitor Specifications

Screen size– The diagonal measurement of the screen surface in inches (15, 17, 19, 21).

Resolution– The sharpness of the images on the screen determined by the number of horizontal and vertical pixels that the screen can display (800x600, 1024x768, 1600x1200).

Dot pitch– The distance between each pixel on the screen measured in millimeters (.22mm, .25mm, .28mm).

Refresh rate– The speed at which the screen is redrawn (refreshed) measured in Hertz (Hz) (60Hz, 75Hz).

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Printers

A printer is a peripheral device that produces a physical copy or hard copy of the computer’s output.

Two basic types: Impact printer Nonimpact printer

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Impact Printer

An impact printer is a printer that has a print head that contacts the paper to produce a character.

It uses ink ribbon.

It is noisy, produces Near-letter quality printouts, and is not commonly used today.

Dot-matrix– Pins are used to make characters.

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Impact printer Dot-matrix

Nonimpact Printer

The nonimpact printer is the most commonly used printer today. It works quietly compared to an impact printer. Two types of nonimpact printers:

Inkjet printer– Also called bubble-jet; makes characters by inserting dots of ink onto paper; letter-quality printouts; cost of printer is inexpensive but ink is costly.

Laser printer works like a copier; quality determined by dots per inch (dpi) produced; color printers available; expensive initial costs but cheaper to operate per page.

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Inkjet Laser

Multifunction Printer

A multifunction printer combines the functions of a nonimpact printer, scanner, fax machine, and copier in one unit.

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Plotter

A plotter is a printer that uses a pen that moves over a large revolving sheet of paper.

It is used in engineering, drafting, map making, and seismotology.

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Audio Output

Audio output is the ability of the computer to output sound.

Two components are needed:

Sound card– Plays contents of digitized recordings.

Speakers– Attach to sound card.

Digital formats include WAV, MPEG, MP3, and MIDI.

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WMA MIDI MP3 WAV

Beethoven 1:15 min

Rocky 2:56 min

Hornsby 48 sec

Cheers 15 sec

Click an icon to play music

Click the icon again to stop playing

Try clicking on Cheers while playing music

Storage

The fourth operation. The computer saves the data or output so that it can be used again

later.

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Memory vs. Storage

Storage, also known as mass media or auxiliary storage, refers to the various media on which a computer system can store data.

Storage devices hold programs and data in units called files.

Files are stored in directories or folders.

Memory is a temporary workplace where the computer transfers the contents of a file while it is being used.

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Hard Drive RAM Memory

Why is storage necessary?

Storage:

Retains data when the computer is turned off.

Is cheaper than memory.

Plays an important role during startup.

Plays an input role when starting applications.

Is needed for output.

Devices can hold a large amount of data.

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Storage Devices

Storage devices are: Hardware that is capable of retaining data when the electricity is

turned off.

Able to read (retrieve) data from a storage medium (disk/tape).

Able to write (record) data to a storage medium.

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How Computers “Think”

Computers use algorithms to solve a problem. Algorithms are step-by-step procedures.

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The Information Processing Cycle

The computer performs the four basic operations (input, processing, output, and storage).

Two types of processing cycles: Batch processing– A lockstep sequence used by older

computers. Interactive processing– Initiating several information

processing cycles in a single session; used by modern computers.

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Input Processing Output Storage

Computer System

A collection of related computer components that are designed to work together.

A system includes hardware and software.

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Hardware Software

Hardware Hardware is the computer’s physical components. The components include:

Input devices– Enable users to enter data into the computer for processing.

Processing circuitry– Components located in the system’s case that transform data into information.

Output devices– Peripherals that show the results of processing.

Storage devices– Used to store all the programs and data that the computer uses.

Communication Devices– Used to move data between computers.

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Processing: Transforming Data into InformationKey Terms

Central processing unit (CPU)– The computer’s processing circuitry. It is also called a microprocessor.

Chip– A wafer of silicon that contains a complex electronic circuit.

Motherboard– The computer’s main circuit board.

Memory– Chips that store program instructions. Random access memory (RAM) is the most important type.

Expansion slots– A receptacle designed to accept a plug-in expansion card.

Expansion card– Used to connect peripherals (input/output devices) to the motherboard.

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Components of the CPU

Control unit– Coordinates and controls all parts of the computer system.

Arithmetic-Logic unit– Performs arithmetic or logical operations.

Registers– Store the most frequently used instructions and data.

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CPUs at Work Control Unit– Manages four basic operations (fetch, decode, execute,

and write-back). The machine cycle or processing cycle:

Instruction Cycle

Fetch- Gets next program instruction from the computer’s memory.

Decode- Figures out what the program is telling the computer to do.

Execution Cycle Execute- Performs the requested action. Write-back (Store)- Writes (stores) the results to a register or to memory.

Arithmetic-Logic Unit (ALU)– Performs basic arithmetic or logic operations.

Adds, subtracts, multiplies, and divides Compares data to determine which one is larger or smaller.

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The Processing Cycle4141

Control unit ALU

Memory

Click to animate. Click one time only

The Motherboard 4242

Microprocessor

Printer Port

Video Port

PCI Slots

Memory Slots

AGP Slot

Chipset

Click on terms to view larger images and informationKeyboard /

Mouse Ports

Popular CPUs 4343

Intel Advanced Micro Devices (AMD)

Cyrix Motorola (Apple)

Pentium IV

Pentium MMX

Pentium III

Processing Devices4444

Motherboard

Central Processing Unit– CPU

Random Access

Memory– RAM

Expansion Card

Output: Displaying the InformationKey Terms

Monitors– Display processing results on a screen.

Cathode ray tube– Monitor similar to televisions.Flat-panel displays (LCD)– Monitor that uses liquid crystal

diodes.

Speakers– Enable the user to hear the results of sound processing.

Printers– Generate output on paper.

Impact printers– Print heads strike a ribbon to produce an image.

Nonimpact printers– Transfer the image to the paper. Inkjet printers Laser printers

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Output Devices4646

MonitorPrinter

Speakers

Storage: Holding Programs and Data for Future Use

Key TermsStorage media– Includes all types of storage media.Magnetic storage media– Uses magnetically sensitive material.Optical storage media– Uses a laser beam to scan pits etched

into a disc.

Writing– Recording data to a disk.

Reading– Playing back information on a disk.

Floppy disk– Removable storage medium.

CD ROM– Optical storage medium.

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Storage Devices4848Hard Drive

Floppy Disk Drive

Zip Drive

CD / DVD Drive

Jazz Drive

Tape Drive

Micro Drive

Communications Devices

Key Terms

Computer network– Two or more computers linked by some type of connection.

Modem– Enables access to other computers by way of a telephone line.

Network interface card (NIC)– Enables computers to connect to each other in a limited geographic area.

Local area network (LAN)– Computers connected to each other within a building or group of buildings.

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Communications Devices 5050

ModemNetwork Interface Card– NIC

Types of Computers 5151

Desktop– PC, Microcomputer

Notebook– Laptop

Workstation

Personal Digital Assistant– PDA, Handheld, Pocket PC