Introduction To Computer System

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Introduction To Computer System
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Computer Generations

• First
• Second
• Third
• Fourth

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Computer Generations
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The First Transistor (1948)
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IBM 360 Computer System
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IBM 704
Used discrete transistors
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IBM 709 Mainframe
Last of the vacuum tube computers, c. 1959
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Digital Equipment Corp
Left DEC PDP-8, c. 1965 Right DEC PDP-11, c.
1970
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Computer

• What is the Computer ?
• The Computer is a set of independent physical
  components and devices (Hardware), which have a
  specific job to do for each one and working
  together by Software to make up the computer
  system.
• Computer perform three main operations

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Computer Classifications (types)

• Microcomputer
• Minicomputer
• Mainframe
• Supercomputer

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Microcomputer

• Users One
• Speed Slow
• Price 500 - 3,000
• Size desktop or smaller
• Examples IBM PC, Apple , Apple Macintosh,
  Imac
• personal computers

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Minicomputer

• Users 2 - 50
• Speed Faster
• Price 10,000 - 250,000
• Size file cabinet
• Examples HP 9000
• DEC VAX
• departmental computers

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Mainframe Computer

• Users 50
• Speed Fast
• Price 500,000 - millions
• Size refrigerator-sized on up
• Examples IBM 3090, Unisys 2200
• company-wide (enterprise)

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Supercomputer

• Users a few
• Speed very, very fast
• Price millions
• Size room
• Examples Cray, Fujitsu
• scientific uses

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Understand the Terms Intelligent and Dumb
Terminal.

• An intelligent terminal, for example a PC -
• Performs a lot of the processing locally
• You could use a PC, linked to a mainframe
• A dumb terminal -
• Has very limited processing capabilities itself,
  but allows you to connect to a large powerful
  computer such as a mainframe.
• When you process your data from the dumb
  terminal, it is the mainframe at the other end of
  the network that is performing all the
  calculations.

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Look inside the computer
SOFTWARE
HARDWARE
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Computers are made of

• HARDWARE
• SOFTWARE

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Hardware
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Hardware

• The parts of computer itself (tangible objects )
  including
• CPU (or Processor) and Primary memory (or Main
  Memory)
• Input devices i.e the keyboard and mouse
• Output devices
• Storage devices

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The Case (System Unit or System Cabinet)
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Hardware

• Central Processing Unit (CPU)
• Input units
• Output units
• Memory (Main or Primary Memory Secondary or
  Auxiliary Memory)

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Components of a Computer System
Central Processing Unit (CPU)
Data
control unit (CU)
Memory
output units
Arithmetic logic Unit (ALU)
RAM
Input units
ROM
Auxiliary Memory
Information/Knowledge
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Hardware Organization
Input Devices ...
CPU
memory
motherboard
hard drive
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Input Devices

• Translate data from form that humans understand
  to one that the computer can work with
• Most common are keyboard and mouse

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Examples of Input Devices

• 1. Keyboard
• 2. Mouse
• 3. Scanner
• 4. Pre-storage Devise (Disk, CDs, etc.)
• 5. Optical mark recognition (Light Pin , Bar
  code scanners)
• 6. Microphone
• 7. Joystick .

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Examples of Input Devices(2)

• 8. Point and Draw devices
• 9. Trackball
• 10. Touchpad
• 11. Touch screen
• 12. Magnetic stripes and smart cars.
• 13. Digital Cameras

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Hardware Organization
CPU
memory
hard drive
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Mother-Board (or Main Board)
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CPU
RAM
ROM
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Hardware Organization
CPU
memory
motherboard
hard drive
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Central Processing Unit (CPU)

• A specific chip or the processor
• a CPU's performance is determined by the rest of
  the computers circuitry and chips.
• The Central Processing Unit (CPU) performs the
  actual processing of data
• The speed (clock speed) of CPU measured by Hertz
  (MHz)

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• The CPU consists of
• Control Unit (CU)
• Arithmetic and Logical Unit (ALU)
• Some Registers

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Central Processing Unit (CPU)
Central Processing Unit (CPU)
Control Unit (CU)
Arithmetic Logic Unit (ALU)
Registers
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• The Control Unit (CU)
• coordinates all activities of the computer by
• Determining which operations to perform and in
  what order to carry them out.
• The CU transmits coordinating control signals to
  other computer components.

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

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Hardware Organization
CPU
memory
motherboard
hard drive
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Primary Memory

• Memory (fast, expensive, short-term memory)
  Enables a computer to store, at least
  temporarily, data, programs, and intermediate
  results.
• Two general parts
• RAM
• ROM

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Know How Computer Memory Is Measured

• Bit
• All computers work on a binary numbering system,
  i.e. they process data in one's or zero's. This
  1 or 0 level of storage is called a bit.
• Byte
• A byte consists of eight bits.
• Kilobyte
• A kilobyte (KB) consists of 1024 bytes.
• Megabyte
• A megabyte (MB) consists of 1024 kilobytes.
• Gigabyte
• A gigabyte (GB) consists of 1024 megabytes.

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Main Memory
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RAM (Main Memory)

• its a primary storage or random access memory
  (RAM).
• it temporarily holds data and programs for use
  during processing (volatile)
• Any information stored in RAM is lost when the
  computer is turned off.
• RAM is the memory that the computer uses to
  temporarily store the information as it is being
  processed. The more information being processed
  the more RAM the computer needs.
• RAM consists of locations or cells. Each cell
  has a unique address which distinguishes it from
  other cells.

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ROM Read Only Memory

• ROM is part of memory
• Programmed at manufacturing time
• Its contents cannot be changed by users
• It is a permanent store
• Q Mention some examples of ROM?
• A (PROM EPROM )

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Other Kind of Memory

• PROM Programmable Read Only Memory.
• EPROM Erasable Programmable Read Only Memory
• Cache Memory
• Registers not part of the main memory.
• Q Registers are part of ?

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Secondary Storage

• Stores data and programs permanently its
  retained after the power is turned off
• Examples
• Hard Drive (Hard Disk)
• Located outside the CPU, but most often
  contained in the system cabinet
• Floppy Disk
• Optical Laser Discs
• CD-ROM, CD-RW, and DVD

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Kinds of Disk Drives
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Common 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 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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Optical Laser Discs

• CD ROM DVDs
• Data is represented as pits and lands
• Some kinds are read only (CD-ROM) and some Kinds
  are rewritable (CD-RW)
• Significantly more capacity and faster operating
  than diskettes

DVD Digital Video Disk
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Common Secondary Media
Approximate printed 8.5 x 11 inch pages Amount of storage Disk size
180 pages 360 Kb 5.25 low density
360 pages 720 Kb 3.5 low density
600 pages 1.2 Mb 5.25 high density
720 pages 1.44 Mb 3.5 high density
a small library 700 MB CD
a feature length movie 8.5 GB DVD
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Common Secondary Media

• tapes
• Panasonic's LS120 3.5 inch diskettes
• Iomega's Zip Jazz disks
• VCR tape (Video Cassette Recorder )
• Flash USB disks
• MMC (Multi Media Card )
• SD

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Hardware Organization
CPU
memory
hard drive
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Output
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CPU
Output Devices
Pieces of equipment that translate the processed
information from the CPU into a form that humans
can understand.
Processed information
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Output Devices

• Monitors
• Printers
• Dot matrix printers
• Ink jet printers
• Laser printers
• Sound Blasters (Sound Card By Creative Lab)
• Controlling other devices

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Software

• The instructions that tell the computer what to
  do
• Application Software - helps end-users perform
  general purpose tasks
• System Software - enables application software to
  interact with the computer

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System Software

• The most important
• System Software
• is the
• Operating System
• Examples of operating systems
• Windows XP, DOS, Apple, UNIX

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System Software

• The software that controls everything that
  happens in a computer.
• Background software, manages the computers
  internal resources

Resources examples CPU, RAM , I/O devices,
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• All hardware and software are under the control
  of the operating system.
• Among other things, the operating system
• Determines how valuable RAM is allotted to
  programs.
• Performs tasks related to file management.
• Sets priorities for handling tasks.
• Manages the flow of instructions, data and
  information to and from the processor (CPU).

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Examples of Microcomputer Operating System
Software

• DOS - original standard for IBM compatibles
• Windows - a graphical operating environment
• Windows VISTA, XP, millennium, 2000, 98, and 95
• Continue

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Examples of Microcomputer Operating System
Software Cont.

• Windows NT - for powerful workstations networks
• OS/2 - competitor to Windows 2000
• Macintosh Operating System
• Unix - originally for minicomputers, now used on
  microcomputers and Internet servers
• Question List some examples of operating systems
  ?

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Application Software
Packaged
Custom

• Packaged - off the shelf, pre-written programs
  ( General purpose)
• Custom - written for an organizations specific
  purpose (Special purpose)

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Application Software Basic Tools

• Word processors example Microsoft word
• Spreadsheets-- example Microsoft Excel
• Database managers-- example Microsoft Access
• Graphics-- example Photoshop

Spreadsheets Computer software that allows the
user to enter columns and rows of numbers in a
accounting book like format.