Chapter 9 Selection of Hardware

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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

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9.1 Types of Computers
Chapter 9 Selection of Hardware

• Computers can be generally classified by size and
  power as follows
• 1. Handheld Computers
• 2. Personal Computers
• 3. Minicomputers and Mainframes
• 4. Supercomputers

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9.1.1 Handheld Computers
9.1 Types of 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

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9.1.2 Personal computers (1)
9.1 Types of Computers

• 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

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9.1.2 Personal computers (2)
9.1 Types of Computers

• 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

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9.1.3 Minicomputers/Mainframes
9.1 Types of Computers

• 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

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9.1.3 Supercomputers
9.1 Types of Computers

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

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9.2 Performance of a Computer
Chapter 9 Selection of Hardware

• 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

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9.2.1 Clock speed
9.2 Performance of a Computer

• 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

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9.2.2 RAM and Performance (1)
9.2 Performance of a Computer

• 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 ...

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9.2.2 RAM and Performance (2)
9.2 Performance of a Computer

• 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

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9.2.3 Other factors that affect the performance
9.2 Performance of a Computer

• 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

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9.3 Hardware for different purposes
Chapter 9 Selection of Hardware

• 1. Home Users or SOHO
• 2. Mobile Users
• 3. Schools
• 4. Supermarkets
• 5. Designed for disabilities

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9.3.1 Home users/SOHO (1)
9.3 Hardware for Different Purposes

• 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.

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9.3.1 Home users/SOHO (2)
9.3 Hardware for Different Purposes

• Output devices
• 17"-19" monitor
• Inkjet printer/ colour laser printer
• Speaker
• Storage devices
• CD-RW writer for both reading and recording CDs

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9.3.2 Mobile users
9.3 Hardware for Different Purposes

• 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

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9.3.3 Schools (1)
9.3 Hardware for Different Purposes

• 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

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9.3.3 Schools (2)
9.3 Hardware for Different Purposes

• 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

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9.3.4 Supermarkets (1)
9.3 Hardware for Different Purposes

• 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

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9.3.4 Supermarkets (2)
9.3 Hardware for Different Purposes

• 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

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9.3.5 Computer facilities for disabled (1)
9.3 Hardware for Different Purposes

• 1. Visually impaired
• screen-enlarging software
• voice output software
• Braille display
• large-size LCD monitors

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9.3.5 Computer facilities for disabled (2)
9.3 Hardware for Different Purposes

• 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