IB Topic 1

• A Computer System is composed of both hardwares and softwares
• Hardwares include: the CPU, memory (RAM, ROM, storage devices), and Input/output devices
• Softwares include: system softwares and application softwares
• A CPU is the brain of the computer, it processes instructions given by softwares
• Primary storage includes the RAM and ROM, they can be directly accessed by the CPU.
• RAM is volatile whereas ROM is non-volatile. ROM permanently stores instructions on your computer.
• Storage devices could be optical, magnetic, or solid-state
• System Softwares are operating systems that manage hardware resources (e.g Linux, macOS, Windows)
• Application Softwares are programs that perform specific tasks for users (e.g web browsers, word processors)
• What to Consider when Changing to a New System

  • The Cost of Change

  • Amount of Change Planned

  • The Limitations of the New System

  • Context in which the system will be used
• Difficulties in Changing Softwares

  • High cost

  • Features may be lost

  • Some users may not like the change

  • Data loss risks

  • Incompatibility (w/ other systems)

  • Old systems may be faster
• 4 Ways of Changing Softwares

  Direct changeover, Parallel, Pilot, and Phased
• Direct Changeover


  The old system is stopped, and the new system is started
• Parallel


  Both the old and the new system is run concurrently, new data is entered into both
• Pilot


  The new system is pilot-tested in a small part of the organisation. After the bugs are fixed and they get used to the system, they expand it wider into the organisation.
• Phased


  The software’s features are introduced in phases, as the old system is gradually phased out