Multitasking

Multitasking, in computer science, a mode of operation offered by an operating system in which a computer works on more than one task at a time. There are several types of multitasking. Context switching is a very simple type of multitasking in which two or more applications are loaded at the same time but only the foreground application is given processing time; to activate a background task, the user must bring the window or screen containing that application to the front. In cooperative multitasking, exemplified by the Macintosh operating system, background tasks are given processing time during idle times in the foreground task (such as when the application waits for a keystroke), and only if the application allows it. In time-slice multitasking each task is given the microprocessor's attention for a fraction of a second. To maintain order, tasks are either assigned priority levels or processed in sequential order. Because the user's sense of time is much slower than the processing speed of the computer, time-slice multitasking operations seem to be simultaneous. Examples of operating systems that use time-slice multitasking are OS/2 and Windows NT.