Computer multitasking

In computing, multitasking is a method where multiple tasks (also known as processes) are performed during the same period of time – they are executed concurrently (in overlapping time periods, new tasks starting before others have ended) instead of sequentially (one completing before the next starts).

(TO DO: organize, illustrate, cross-reference.)

Description

The tasks share common processing resources, such as central processing units (CPUs) and main memory.

Multitasking does not necessarily mean that multiple tasks are executing at exactly the same instant: multitasking does not imply parallel execution.

Multitasking means that more than one task can be part-way through execution at the same time, and that more than one task is advancing over a given period of time.

In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is actively executing instructions for that task.

Multitasking solves the problem by scheduling which task may be the one running at any given time, and when another waiting task gets a turn.

The act of reassigning a CPU from one task to another one is called a context switch. When context switches occur frequently enough, the illusion of parallelism is achieved.

External Links

• Computer multitasking @ Wikipedia