Multitasking

Even if your computer can be seen in a gigantic program stored in main memory, on some systems, you need to give the appearance to run multiple programs simultaneously. This is achieved by multi-tasking, or take your computer to switch rapidly between running each program in turn.

A means by which this is done is with a special signal called an interrupt which can periodically cause the computer to stop executing instructions where it was and do something else. Remembering where he played before the interruption, the computer can return to that task later. If multiple programs are running "on time" and disconnect the generator can cause several hundred interrupts per second, causing a control program every time. Since modern computers typically execute instructions several orders of magnitude faster than human perception, it may seem that the programs running at the same time, although no one is ever playing at any given time. This method of multitasking is sometimes called "time-sharing" since each program assigned a "slice" of time to come.

Seemingly, multitasking would cause a computer to switch between different programs to run more slowly - in direct proportion to the number of programs are underway. Most programs spend much of their time waiting for slow input / output devices to perform their tasks. If the program expects the user clicks with the mouse or press the button, so you do not take "slices of time" until the event is expected to place. This is the time spent on other programs in a way that many programs can run simultaneously without loss of speed is unacceptable.