Structure of A Computer

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Structure of A Computer

• ---Prof. Jianfeng Wang

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What is a computer?

• A computer is defined as an electronic device
  that accepts input, processes data, stores data,
  and produces output.
• A computer system includes a computer, peripheral
  devices, and software.

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Hardware

• The physical components of a computer are
  referred to as hardware.
• The design and construction of a particular
  computer is referred to as its architecture, or
  configuration.
• The technical details about each component are
  called specification

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Software

• Software refers to the intangible components of a
  computer system, particularly the programs, or
  lists of instructions, which the computer needs
  to perform a specific task.

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Computer hardware

• Input devices
• Output devices
• Motherboard
• Processing hardware
• Microprocessor,
• RAM, and
• ROM
• Storage media

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Input devices

• keyboard types102, 104, and 104 buttons
• pointing devices mouse, touch pad/track
  point/track ball, pointing stick, joystick and
  wheel, cordless mouse
• light pen, touch screen, voice input.
• Input devices for handheld computers on-screen
  keyboard, digital camera, etc

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Output devices

• Monitor, printer, voice/sound output

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Processing hardware

• Data representation
• Storage and memory capacity
• Microprocessor

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Data representation

• The computer only recognize two states. The
  binary system is a number system having just two
  digits 0 and 1.
• ASCII code American standard for information
  interchange, the most widely used coding system
  to represent data

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Data representation

• EBCDIC Extended binary coded decimal interchange
  code, is primarily used on mainframe computers.

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Storage and memory capacity

• Storage and memory capacity is the amount of
  data, or number of characters, that the device
  can handle at any given time.

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Storage and memory capacity

• A kilobyte (KB) is 1024 bytes,
• A megabyte (MB) is 1024 KB.
• A gigabyte (GB) is 1024 MB.
• A Terabyte (TB) is 1024 GB.
• A petabyte (PB) is 1024 TB.

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Processor Box
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A mother board
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Microprocessor

• CPU central unit processor, its performance
  depends on its clock speed, word size and cache
  size.
• Cache, is a special high-speed memory mechanism.
• Clock speed as the pulse of the processor, is
  measured in millions of ticks per second. We are
  now talking about 1 3.6 GHz for PC. But 7 years
  ago most PCs only ran at 32 MHz.

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Memory RAM

• RAM---- random access memory. A conventional
  computer memory that can be used by programs.
• SRAM and DRAM
• Is a circuit-integrated chip that allows data to
  be stored and accessed randomly and all storage
  locations are equally accessible.

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SRAM static RAM

• Static RAM is a type of RAM that holds its data
  without external refresh, for as long as power is
  supplied to the circuit.
• SRAM is faster than DRAM
• SRAM is, byte for byte, several times more
  expensive than DRAM.
• 32 MB of SRAM would be prohibitively large and
  costly

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SRAM as Cache

• Frequently visited data will be stored at cache.
  When you next time access the same data, the
  computer will first check whether the data is
  available at cache. If it is stored at cache, the
  data can be accessed very quickly. It is very
  slow to retrieve data from hard disk. Thats why
  we need cache.

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DRAM Dynamic RAM

• Dynamic RAM is a type of RAM that only holds its
  data if it is continuously accessed by special
  logic called a refresh circuit.
• If this is not done regularly, then the DRAM will
  lose its contents, even if it continues to have
  power supplied to it. This refreshing action is
  why the memory is called dynamic.

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Memory ROM

• ROM ----Read only memory. A pre-recorded chip,
  data on ROM can only be read.

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Disk and Tape

• Hard disk, Memory Stick, Floppy A disk, Compact
  Disk, Zip disk with zip drive, and Tape.
• USB memory stick is a versatile flash memory
  card. A high capacity and high performance
  memory card.

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Cost and speed of different storage media and
memory

• RAM
• Hard disk Faster
• More expensive CD
• Floppy Disk
• Cheaper Tape Slower

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Data Communication

• The transmission of text, voice, or video data
  from one component device to another is called
  data communication.
• What is Data bus?
• What is Word size

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Data bus

• Starting at the microprocessor and passing
  through a continuous channel, the data travels
  out to the appropriate device. From an input
  device back to the microprocessor, the path is
  reversed. These communication channel between the
  microprocessor, RAM, and the peripherals is
  called data bus.

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Data bus

• Bus allows the various devices inside and
  attached to the system unit to communicate with
  each other. Just as vehicles travel on a highway
  to move from one destination to another, bits
  travel along on a bus.

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Data bus

• The size of a bus, called the bus width,
  determines the number of bits that the computer
  can transmit at one time.
• 32-bit bus
• can transmit 32 bits at one time.
• 64-bit bus
• can transmit 64 bits at one time.

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Word size

• Word size is the number of bits the processor can
  interpret and execute at a given time such as in
  1 nanosecond.

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Port and Cable

• A port is the interface, or point of attachment,
  to the system unit.
• An external device such as a keyboard, monitor,
  printer, mouse, and microphone, often attach to
  the system unit by a cable.
• Microcomputer can have several types of ports,
  including USB, parallel, serial, SCSI, and MIDI.

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Serial Port

• A serial port is used to connect external modems.
  It comes in two versions a 9-pin version (on the
  left) or a 25-pin model. The 9-pin is found on
  most newer computers. Data travels over a serial
  port at 115 kilobits per second.

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Parallel Port

• A parallel port is used to connect external
  devices such as scanners and printers.

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Other components Video Card
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Reference

• Visit following websites for more information
• http//www.cyberwalker.net/connectors/index.html
• http//www.pcguide.com/proc/pcassy/