The Computer System The computer is an automatic, electronic device that accepts data or input,

which it stores and processes to give output or

information

What are the functions of the computer system?

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Types of Computers

Mainframe Mini Computers Super Computers Micro Computers

Personal Computers Embedded Computers Laptops, notebooks, netbooks Palmtop Computers Tablet PC

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Mainframe Computer

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Mini Computer

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Supercomputer

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Micro Computers

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Functions of a Computer System

INPUTPROCESSIN

GOUTPUT

STORAGE

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The Computer System - Again

INPUT

OUTPUT

MEMORY

CPU

Control Unit (CU)

Arithmetic & Logic Unit

(ALU)

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InputThe medium through which data is sent to the computer for processing.

Sources of Input

Data from Human users

Data from MachinesBack to functions

Input Devices

Keyboard/Keypad Pointing Devices

Mouse Trackball Pointing Stick Touchpad **Joystick Touch Terminal Graphic Tablet Light Pen

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Input

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Input Devices

Scanning DevicesScanner

Flatbed, hand-held, Drum, Sheet-fed

Barcode ReaderScanning Facilities

OCROMRMICR

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Scanners

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Input DevicesDigital Still-Shot CameraDigital Video CameraWebcamSmart CardBiometric SystemsRemote ControlSensors Interactive Whiteboards

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Other Input Devices

Input Devices

Audio Input Devices Microphone RFID – Radio Frequency Identification MIDI

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Audio Input Devices

Input Devices

Gaming Input JoystickGaming padGaming WheelLight gunDance PadMotion Sensing controllers

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Gaming Input Devices

Output Output is the result of processing. It

is the purpose you set out to achieve by using the computer.

Output Devices are pieces of equipment that are used to communicate output/information.

Types of Output Soft copy Hard Copy

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Output Devices

VDU

Printers

Microfilm/Microfiche

Audio Output

Robot/Control Systems

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VDU – Visual Display Unit The Screen is made up of Pixels Types

CRT (Cathode Ray Tube) Flat Panel Display

LCD (Liquid Cristal Display) Plasma Display

Monitor Characteristics VDU Devices

Monitor Multimedia Projector LCD Panel

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Monitors

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Monitor Characteristics

Monitor Size Display Resolution

VGA (640 X 480) – Video Graphics Array SVGA(800 X 600) – Super Video Graphics Array XGA/XVGA (1024 X 768) – Extended Video

Graphics Array SXGA (1280 X 1024) – Super Extended Graphics

Array UXGA (1600 X 1200) – Ultra Extended Graphics

Array QXGA (2048 X 1536) – Quad Extended Graphics

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Monitor Characteristics

Image Aspect Ratio Ratio width to height

Refresh Rate Number of refresh times/second

Video or graphics card or adaptor Links processor and monitor

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Sound Output

Speakers Headphones Earphones / ear buds

Voice Response Systems

Speech Synthesis Conversion of text to speech

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Sound Output Devices

Printers

Producer of Hardcopy output Classification 1:

Character printers Line Printers Page Printers

Classification 2: Impact Printers Non-impact Printers

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Impact Printers

Dot Matrix

Daisy Wheel

Drum, Chain or Band Printer

Braille Printer

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poster

Non – Impact Printers

Thermal

Laser

Inkjet

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Other Printers

Mobile Printers Multifunctional Printers Plotters

Pen Plotters Inkjet Plotters Electrostatic Plotters

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Microfiche/Microfilm (COM)

COM – Computer Output on Microfilm/Microfiche

Microfilm: Roll of film

Microfiche: Sheet of film

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Robot and Control Systems

Processor to Robotic hardware produces physical action and is therefore a type of output.

Control Systems uses sensors as input and activates an item of hardware as a result of the input received

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Storage

Media and Devices used to keep data and instructions available for immediate or later use.

Categories of Storage Primary (Main Memory) Secondary

Units of Storage

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Primary Storage

Also called main memory Memory chips (integrated circuit) is

immediate access store and resides in the motherboard

RAM Temporary and changeable (volatile) Holds programs and data currently being used

Cache High speed static RAM (SRAM) Easier to access than primary memory Speeds up processing

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Primary Storage

ROM Chips holding instructions needed for

starting up the computer Non volatile (not easily modified)

Variations of ROM PROM EPROM EEPROM

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Units of Storage – see pg 31 Bit (Binary Digit) Byte Character Word Word length

Larger Units Kilobyte Megabyte Gigabyte Terabyte Petabyte Exabyte Zettabyte yottabyte

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Secondary Storage

Also known as auxiliary or backup storage, keeps data and information even while the computer is switched off

Classifications by technology Magnetic Optical ROM

Classification by Access type Serial Access Direct Access

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Storage Media Magnetic Tapes

Magnetic Disks Floppy Disks Hard Disks

Optical Disks CD (ROM; R; RW) DVD Blu-Ray

Flash MemoryBack to Storage

Storage Media Pgs 32 - 37 Magnetic Tapes

Includes microfilm

Magnetic Disks Floppy Disks Hard Disks

Access time; tracks, sectors, cylinders

Optical Disks CD (ROM; R; RW) DVD Blu-Ray

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Storage Devices

Optical Disk Drive Tape Drive

Connectivity **USB Drive FireWire

`

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True / False

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CPU

VDU

The CPU Also known as the

processor Takes raw data and

following instructions, converts it to information

Speed is measured in megahertz

Consists of the Control Unit and the Arithmetic Logic Unit

CPU

Control Unit (CU)

Arithmetic & Logic Unit

(ALU)

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Control Unit

Directs and co-ordinates all activities within the CPU Fetches instructions from memory Decodes the instructions Fetches required data Sends data and instructions to ALU

for processing Sends data to main memory after

processing

Arithmetic Logic Unit

Performs ALL arithmetic and logical functions of the computer

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