O Level Computer Science: Software: Operating Systems: Personal Computers

• A personal computer operating system is a software which is initially installed in a personal computer which has a role of controlling the operation of a computer and directing the processing of programs as by assigning storage space in memory and controlling input and output functions.
• Examples of personal computer operating systems include Windows 95/98/2000/XP/VISTA/ Windows 7/Windows 8/Windows 10, Microsoft Disk Operating System (MS-DOS), Unix, Linux, OS/2, Ubuntu, etc.
• The personal computer operating system has various roles which include:
  •  Management of the processor: the operating system is responsible for managing allocation of the processor time between the different programmes using a scheduling algorithm.
  • Management of the random access memory: the operating system is responsible for managing the memory space allocated to each application and, where relevant, to each user. If there is insufficient physical memory, the operating system can create a memory zone on the hard drive, known as “virtual memory”. The virtual memory lets you run applications requiring more memory than there is available RAM on the system. However, this memory is a great deal slower.
  •  Management of input/output: the operating system allows unification and control of access of programmes to material resources via drivers (also known as peripheral administrators or input/output administrators).
  •  Management of execution of applications: the operating system is responsible for smooth execution of applications by allocating the resources required for them to operate. This means an application that is not responding correctly can be “killed”.
  •  Management of authorisations: the operating system is responsible for security relating to execution of programmes by guaranteeing that the resources are used only by programmes and users with the relevant authorisations.
  •  File management: the operating system manages reading and writing in the file system and the user and application file access authorisations.
  •  Information management: the operating system provides a certain number of indicators that can be used to diagnose the correct operation of the machine.

To access more topics go to the O Level Computer Science Notes page