the role of ict

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Components of an Information System

Difference between Hardware and Software

  • Hardware:
  • Physical equipment that makes up a computer system
  • If you can kick it or take an axe to it it is hardware.
  • Software:
  • Programs, routines and procedures (together with their associated documentation) which can be run on a computer system.

It is important not to confuse the media used to transport software with software itself

  • A CD is a piece of hardware which you can touch and kick and it may contain software which you cannot touch.  
  • The CD is not software it is hardware

Examples of Hardware

  • Central Processor
  • Peripherals – these are hardware devices which are attached to the central processor:
  • They can be classified into four types:

Input:

  • Keyboard, Mouse, Scanner

Output:

  • Monitor, Speakers

Backing Storage:

  • Hard Disk, Floppy Disk Drive

Communications:

  • Modem

Hardware & Software Standardisation

In general, hardware produced by one company will not be compatible with that produced by another

Hardware:

  • A POS terminal by IBM could not plug into an ICL system

Software:

  • A program written for the Mac would not run on a PC

Software standardisation

  • Output may appear different:
  • E.g. web pages viewed on different systems

Different layout, resolution of images, etc.

  • Standardisation of file formats
  • Importing and exporting of data between applications

  • Advantages of Standardisation
  • Hardware and software will be known to be compatible
  • Choices from where to purchase equipment
  • Agreed standards for equipment – comeback if not up to standard
  • Disadvantages of standardisation
  • Less choice
  • Less competition amongst suppliers

Components of the Central Processing Unit ( CPU )

  • Control Unit
  • This is the part of the central processor (CPU) which manages the execution of instructions.  The control unit fetches each instruction in sequence, decodes and synchronises it before executing it by sending control signals to other parts of the computer.
  • Arithmetic and Logic Unit (ALU)
  • This is the part of the CPU where data is processed and manipulated.  This consists of arithmetic and logic operations.
  • Random Access Memory (RAM)
  • Memory which holds data loaded from the backing store – data that the computer is to process, screen display etc.

Computer Performance

Machine Cycle

  • A computer runs on a clock – a 2.5 GHz machine is running at 2.5 thousand million cycles per second.  Each cycle is a clock pulse.  The faster the clock, the more instructions per second.
  • The complexity of the instructions affects the speed of processing.
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  • A program consisting of a larger number of simple instructions drawn from a reduced instruction set (RISC) may run faster than an equivalent program consisting of a smaller number of complex instructions drawn from an extended instruction set (CISC).

Number of Processors

  • A single processor can only run 1 instruction at a time.  To get beyond this you need an additional processor.  This allows more than one instruction to be run and increases the speed of the computer.  Programs and computers have to be written to make use of the second processor.

Bus Speed

  • The ...

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