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Hardware - devices forHardware - devices for

•Input

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Hardware - devices forHardware - devices for

• Input

• Processing

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Hardware - devices forHardware - devices for

• Input• Processing

• Storage

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Hardware - devices forHardware - devices for

• Input• Processing• Storage• Output

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Hardware - devices forHardware - devices for

• Input• Processing• Storage• Output• Communications

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Input DevicesInput Devices• Translate data from form that

humans understand to one that the computer can work with

• Most common are keyboard and mouse

Selector Buttons

ExamplesExamples of Input of Input DevicesDevices

1.1. KeyboardKeyboard 2. Mouse2. Mouse 3. Scanner3. Scanner 4. Pre-storage Devise (Disk, CD’s, … 4. Pre-storage Devise (Disk, CD’s, …

etc.)etc.)5. Optical mark recognition (Light 5. Optical mark recognition (Light

Pin , Bar code scanners)Pin , Bar code scanners)6. Microphone 6. Microphone 7. Joystick .7. Joystick .

8. Point and Draw devices 8. Point and Draw devices

9. Trackball9. Trackball

10. Touchpad10. Touchpad

11. Touch screen 11. Touch screen

12. Magnetic stripes and 12. Magnetic stripes and smart cars. smart cars.

13. Digital Cameras 13. Digital Cameras

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The System UnitThe System Unit

•Electronic circuitry within the computer cabinet

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The System UnitThe System Unit• Two general parts

Central Processing Unit (CPU) - an integrated micro-circuit that translates data into information

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The CPU consists of :The CPU consists of :Control Unit (CU)Control Unit (CU)Arithmetic and Logical Arithmetic and Logical Unit (ALU)Unit (ALU)

Some Registers.Some Registers.

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The Control Unit (CU) within a The Control Unit (CU) within a CPU coordinates all activities of CPU coordinates all activities of the computer by determining the computer by determining which operations to perform and which operations to perform and in what order to carry them out. in what order to carry them out. The CU transmits coordinating The CU transmits coordinating control signals to other computer control signals to other computer components.components.

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The ALU consists of electronic The ALU consists of electronic circuitry to perform arithmetic circuitry to perform arithmetic operations (addition, operations (addition, subtraction, multiplication and subtraction, multiplication and division), logical operations division), logical operations (and, or, not, …) and to make (and, or, not, …) and to make some comparisons (less-than, some comparisons (less-than, equal, … etc.)equal, … etc.)

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The System UnitThe System Unit

• Two general parts

•Memory - referred to as primary storage or random access memory (RAM), it temporarily holds data and programs for use during

processing (volatile)

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RAMRAM

RAM consists of locations or RAM consists of locations or cells. Each cell has a unique cells. Each cell has a unique address which distinguishes address which distinguishes it from other cells.it from other cells.

Main MemoryMain Memory

Address Memory locations

1

2

3

n

Memory Cell

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ROM: Read Only MemoryROM: Read Only Memory

ROM is part of memory.ROM is part of memory.

Programmed at Programmed at manufacturing timemanufacturing time

Its contents cannot be Its contents cannot be changed by userschanged by users

It is a permanent storeIt is a permanent store

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Secondary StorageSecondary Storage• Stores data and programs

permanently: its retained after the power is turned off

• Located outside the CPU, but most often contained in the system cabinet

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Three Kinds of Disk DrivesThree Kinds of Disk Drives

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Common Secondary MediaCommon Secondary Media• Diskettes

– Data represented as magnetic spots on removable flexible plastic disks

– Most common size is 3 1/2 inches, in a rigid plastic case

– Disk drive holds the diskette, reads or retrieves the data and writes or stores data

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Common Secondary MediaCommon Secondary Media• Hard drive

– Data is represented magnetically as with diskettes

– Normally more than one rigid platter in a sealed unit

– These disks are not removable– Significantly more capacity and faster

operating than diskettes

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Output DevicesOutput Devices

Pieces of equipment that translate the processed information from the CPU into a form that humans can understand.

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Output DevicesOutput Devices

MonitorsMonitors PrintersPrinters

Dot matrix printersDot matrix printersInk jet printersInk jet printersLaser printersLaser printers

Sound plastersSound plasters Controlling other devices Controlling other devices

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Communications DevicesCommunications Devices

Hardware that sends and receives data and programs from one computer or secondary storage device to another.

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Units of MeasurementsUnits of Measurements

Bit Bit (Binary Digit)(takes two values: 1 or 0)(Binary Digit)(takes two values: 1 or 0)Byte = 8 bitsByte = 8 bitsKB (Kilo-byte) = 1024 bytesKB (Kilo-byte) = 1024 bytesMB (mega-byte) = 1024 KBMB (mega-byte) = 1024 KBGB (giga-byte) = 1024 MBGB (giga-byte) = 1024 MBTB (Tera-byte) = 1024 GBTB (Tera-byte) = 1024 GB

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ConnectivityConnectivity

The computer’s capability to send and receive information from other locations.

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Systems of interconnected Systems of interconnected computers, known as networks, are computers, known as networks, are the sources of distant information.the sources of distant information.

ConnectivityConnectivity

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Systems of interconnected computers, known as Systems of interconnected computers, known as networks, are the sources of distant information.networks, are the sources of distant information.

The National Information Infrastructure (NII) is currently the Internet.

ConnectivityConnectivity

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Computer VirusesComputer Viruses

A computer virus is an application A computer virus is an application program designed and written to program designed and written to destroy other programs. destroy other programs.

- It has the ability to:- It has the ability to: Link itself to other programsLink itself to other programs Copy itself (it looks as if it repeats Copy itself (it looks as if it repeats

itself)itself)

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Examples of VirusesExamples of Viruses

MonkesMonkesABCABCCrabsCrabsCIHCIH

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How do you know if you have How do you know if you have a virus?a virus?

Lack of storage capabilityLack of storage capabilityDecrease in the speed of Decrease in the speed of

executing programsexecuting programsUnexpected error messagesUnexpected error messagesHalting the systemHalting the system

Protection against Computer Protection against Computer VirusesViruses

Buy original copies of software onlyBuy original copies of software onlyMake backups of your filesMake backups of your filesDo not let any body to insert a diskette in Do not let any body to insert a diskette in

your computer unless you are sure they do your computer unless you are sure they do not have any viruses.not have any viruses.

Write-protect your disksWrite-protect your disksUse anti-virus programsUse anti-virus programs