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A high level look at the computer

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• High level view of a computer:

  • A computer system consists of the CPU and Memory.

    (The input and output devices are "peripherals" of the computer system).

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• The CPU:
  • consists of highly complex circuitry to execute instructions (and to perform computations)

  • contains a small amount of high speed memory to store intermediate result of computations.

• The Memory of a computer:
  • Is a "Warehouse", or storage...

  • The memory contains everything needed by the CPU:
    • Stores instructions that the CPU executes

    • Stores data (operands) needed in the instructions

      (data can be constants and variables used in a computer program, including users input & output data)

• Input device:
  • enables users to enter data into the computer

  • many different forms of inputs: keyboard, mouse, scanner, disk files, etc.

• Output device:
  • enables computer to show user outcome of a program

  • many different forms of outputs: terminal, audio beep, graphics, etc.

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• Interconnections between the different components of a computer
  • Copper wires (edged on the "mother board") make connections between components in the computer

  • Wires can be divided into 3 groups according to function:
    1. Wires used to transmit the ID of a device (collectively called the address bus)
    2. Wires used to transmit data between devices (collectively called the data bus)
    3. Wires used to transmit control (commands) information (collectively called the control bus)

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  • A group of wires that are used for a similar function is called a bus
    • address bus (see above)
    • data bus (see above)
    • control bus (see above)
    • system bus = the address, data and control buses collectively