Software classification: processor(s)

The idea

This row is the first item in the list of resources the operating system manages: the processor(s). A computer may have one processor or several cores, and the OS must decide which process uses which core and for how long. It does this through scheduling, giving each process a slice of processor time so that multitasking appears seamless. The OS also handles interrupts, prioritises important tasks and stops one runaway process from monopolising the processor. Distractors may claim the processor manages the OS, that the user manually assigns each instruction, or that application software schedules the processor directly. The plural 'processor(s)' signals that multi-core systems are included.

What earns the marks

• The OS manages the processor(s) by scheduling which process runs and for how long.
• Scheduling gives each process a share of processor time so multitasking appears simultaneous.
• On multi-core systems the OS allocates processes across the available cores.
• The OS handles interrupts and priorities so important tasks are serviced promptly.
• Application software requests processor time from the OS rather than controlling the processor directly.

Common mistakes and how to put them right

• Saying the processor manages the operating system.

  Put it right: , the OS controls and schedules use of the processor.

• Thinking each application directly controls the processor.

  Put it right: , applications request time and the OS scheduler allocates it.

• Ignoring multi-core systems: correction, the plural processor(s) includes allocating work across several cores.

• Confusing processor management with memory management.

  Put it right: , these are separate OS responsibilities even though both are resource management.

Exam tips

• Look for the option describing allocation or scheduling of processor time as the management activity.
• Reject options where hardware or application software is said to control the OS.
• Remember the plural: multi-core allocation is part of processor management.