Threads and Semaphores: 1 Multitasking Goals

The GEOS multitasking system is one of the most sophisticated available for PCs today. It was designed with the latest available technology and was created to serve the following two primary goals:

Fast Response
The GEOS multitasking system was designed with a strong emphasis on rapid response to user input. Prompt, visible reaction to user action is the single most important factor contributing to the perception of speed. For example, if a user changes an element in a spreadsheet (requiring the whole spreadsheet to be recomputed) and then pulls down a menu, he wants the menu to appear right away. If the menu does not appear until the computation is finished, the system will seem sluggish. If the computation takes a few seconds or longer, the user may wonder whether the system has crashed altogether.
Ease of Programming
Making the programmer's job easy is another motive behind the design of GEOS multitasking. Ideally, the programmer should not need to be aware that his program will run in a multitasking environment. The program should proceed as though it were the only one running on the system. Besides certain "good citizen" rules, application programs are isolated from the multitasking environment. On the other hand, if a programmer wants to take advantage of the multitasking capability of GEOS (by designing a program to perform more than one task concurrently) the system is designed to make this as simple and efficient as possible.

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