A-level Computing 2009/CIE/Operating Systems

Basic process flow: __________________________________________________________________________________________________________  |                                      | Yes                          | Yes                                | Yes V                                     |                              |                                    | Start - Fetch - Decode - Execute - Check for interrupt - No - Check for more instructions - No - Return to previous instruction? - No - End

Operating system is made out of 4 components:

User interface -  provides an interface for the user to communicate with the hardware

Kernel         -  translates the inputs from the U.I. in Machine Code for the hardware ( device drivers and utilities ) to understand

Device drivers -  The set of instructions that the hardware can understand ( a user manual of the device for the kernel, basically )

Utilities      - Power management, Managing Fragmentation, System Security etc.

The Scheduler

The Scheduler is a part of the OS that manages how much time each process spends using the processor.