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Chapter 9 Selection of Hardware 9.1 Types of Computers 158 9.2 Performance of a Computer 161 9.3 Hardware for Different Purposes 163 Chapter 9 Selection of Hardware 9.1 Types of Computers Computers can be generally classified by size and power as follows:

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chapter 9 selection of hardware

Chapter 9 Selection of Hardware

9.1 Types of Computers 158

9.2 Performance of a Computer 161

9.3 Hardware for Different Purposes 163

9 1 types of computers

Chapter 9 Selection of Hardware

9.1 Types of Computers
  • Computers can be generally classified by size and power as follows:

1. Handheld Computers

2. Personal Computers

3. Minicomputers and Mainframes

4. Supercomputers

9 1 1 handheld computers

9.1 Types of Computers

9.1.1 Handheld Computers
  • Handheld Computer
    • also called palm or personal digital assistant (PDA)
    • Pocket-sized device that combines computer, telephone/fax, Internet and networking features.
    • Personal organiser with
      • to-do-list, address book, appointment calendar
    • Pen-based
      • Using a stylus rather than a keyboard for input
      • With
        • handwriting recognition, or
        • voice recognition
9 1 2 personal computers 1

9.1 Types of Computers

9.1.2 Personal computers (1)
  • Personal computer (PC)
    • Single-user computer
    • Based on microprocessor
  • 1. Notebook computer
    • Also called laptop computer
    • Portable computer
    • Encasing inside a plastic/metal case:
      • Input devices (like keyboard, touch pad/pointing stick)
      • Output devices (like VDU and speaker)
      • Processing unit and other electronic components
    • Tablet PC
      • Input by handwriting on the LCD display
      • Fully functional PC
9 1 2 personal computers 2

9.1 Types of Computers

9.1.2 Personal computers (2)
  • 2. Desktop computer
    • Non-portable
      • The system unit and other peripheral devices can be placed entirely on a desk
    • Desktop computers in a network are called workstations
9 1 3 minicomputers mainframes

9.1 Types of Computers

9.1.3 Minicomputers/Mainframes
  • Minicomputer
    • Multi-user computer
      • supporting from 10 to hundreds of users simultaneously
    • Using time-sharing technology
    • Mid-range server
  • Mainframe
    • Multi-user computer
      • supporting from hundreds or thousands of users simultaneously
    • Using time-sharing technology
    • Enterprise server
  • Server
    • Optimised computer
    • Providing services to other computers over a network
9 1 3 supercomputers

9.1 Types of Computers

9.1.3 Supercomputers
  • Supercomputers
    • Expensive and extremely fast computer
    • Performing hundreds of millions of instructions per second
    • Used in
      • weather forecasting, space research, and military etc.
9 2 performance of a computer

Chapter 9 Selection of Hardware

9.2 Performance of a Computer
  • Besides the processing speed, the performance of a computer also depend on:

1. How often does it fail?

2. Can it perform many tasks at the same time?

3. Can it run complicated software?

4. Are 3D graphics displayed smoothly?

1. Clock Speed

2. RAM and Performance

3. Other Factors

9 2 1 clock speed

9.2 Performance of a Computer

9.2.1 Clock speed
  • Clock speed of CPU
    • Measured in MHz (106 Hz) or GHz (109 Hz)
    • The number of clock cycles or ticks per second
    • The higher is the clock speed, the faster is the computer
      • Because each instruction is processed in a fixed number of clock cycles
9 2 2 ram and performance 1

9.2 Performance of a Computer

9.2.2 RAM and Performance (1)
  • Virtual memory
    • Part of the Hard disk for extending RAM
    • Capacity of RAM is fixed
    • Data not frequently used are moved to the hard disk to make room for new data
      • Return back to the RAM when needed
  • Swapping
    • Moving data between RAM and Hard Disk
    • Done by the computer automatically
    • Transparent to user ...
9 2 2 ram and performance 2

9.2 Performance of a Computer

9.2.2 RAM and Performance (2)
  • Too much Swapping
    • Reduce performance of computer, or
    • Lead to system crash
  • To reduce Swapping
    • Increase the size of RAM
  • Performance of computer also depends on
    • Size of RAM
    • Free space of hard disk
    • Speed of hard disk
9 2 3 other factors that affect the performance

9.2 Performance of a Computer

9.2.3 Other factors that affect the performance
    • Besides 1. Speed of CPU, 2. Capacity of RAM, 3. Speed of hard disk 4. Free space of hard disk, the performance of a computer also depends on
    • 5. Width of Bus System
    • 6. Speed of Peripherals
    • 7. Capability of Video cards
    • 8. Cache memory
  • Cache memory
    • Faster memory
    • Installed between the CPU and the RAM
    • Increasing the speed of memory access
9 3 hardware for different purposes

Chapter 9 Selection of Hardware

9.3 Hardware for different purposes
  • 1. Home Users or SOHO
  • 2. Mobile Users
  • 3. Schools
  • 4. Supermarkets
  • 5. Designed for disabilities
9 3 1 home users soho 1

9.3 Hardware for Different Purposes

9.3.1 Home users/SOHO (1)
  • Desktop PCs with a minimum of 128 MB RAM
    • Or notebook computer with a Docking Station
  • Broadband Internet Access
  • Communication Devices
    • Network interface card (NIC) or
    • Wireless NIC with an access point
    • Fax modem for sending and receiving fax via telephone lines
  • Input devices
    • Image scanner, a digital camera and a camcorder
    • Microphone/Sound card for recording sound
    • Graphic tablet for drawing or inputting Chinese characters.
9 3 1 home users soho 2

9.3 Hardware for Different Purposes

9.3.1 Home users/SOHO (2)
  • Output devices
    • 17"-19" monitor
    • Inkjet printer/ colour laser printer
    • Speaker
  • Storage devices
    • CD-RW writer for both reading and recording CDs
9 3 2 mobile users

9.3 Hardware for Different Purposes

9.3.2 Mobile users
  • Mobile users
    • like sales representatives need
    • Notebook computer or handheld computer
      • with a wireless NIC
      • accessing the Internet in the airport or company's network
    • Portable data projector for presentation
9 3 3 schools 1

9.3 Hardware for Different Purposes

9.3.3 Schools (1)
  • LANs for
    • Administration and Teaching
  • Desktop PCs used in
    • Office, Library, Classrooms and Computer Lab.
  • Notebook computers for
    • Teachers
  • Kiosks
    • Installed in the covered playground/main entrance
  • All computers should have network features
    • Using wireless technology
    • Enough access points for LAN access in the campus
9 3 3 schools 2

9.3 Hardware for Different Purposes

9.3.3 Schools (2)
  • Input Devices
    • Image scanners
    • Graphic tablet for inputting Chinese characters
    • OMR reader for marking multiple choice questions
    • Bar code/magnetic/smart card reader for taking attendance
  • Laboratories
    • Data-loggers (which include sensors and interface)
  • Output Devices
    • Data projectors (ceiling-mounted) in classrooms
    • High speed laser printer; Colour inkjet printer
  • Backing Storage
    • Tape drives for backing up data files in the servers
    • CD-R or CD-RW drives for recording and distributing materials
9 3 4 supermarkets 1

9.3 Hardware for Different Purposes

9.3.4 Supermarkets (1)
  • LAN
    • Connecting together all computers, including those at the Point-of-Sales (POS).
    • Linked to the enterprise server at the head-quarter via dedicated telephone lines.
  • Bar code reader
    • Scanning the bar code of each product
  • Special keyboards
    • Save space and increase the speed of data entry
  • Monitor
    • Small, enough to display necessary information of products
    • Magnetic card/smart card readers for receiving payment
9 3 4 supermarkets 2

9.3 Hardware for Different Purposes

9.3.4 Supermarkets (2)
  • Handheld computers
    • for stock checking
  • Ink-jet printers/laser printers
    • printing price labels on shelf
  • Thermal printer
    • printing price labels for some products, like vegetable
  • Large-format ink-jet printer
    • printing posters
9 3 5 computer facilities for disabled 1

9.3 Hardware for Different Purposes

9.3.5 Computer facilities for disabled (1)
  • 1. Visually impaired
    • screen-enlarging software
    • voice output software
    • Braille display
    • large-size LCD monitors
9 3 5 computer facilities for disabled 2

9.3 Hardware for Different Purposes

9.3.5 Computer facilities for disabled (2)
  • 2. Physical disabilities
    • Movable stools
    • IT equipment that facilitate adjustment of arm and seating positions
    • Touch pad
      • for easy access by people confined to wheelchairs
    • Microphone and voice recognition software
      • eliminate the use of physical devices