There are two main goals of Operating System :-
The primary goal of some operating system is convenience for the user. While the primary goal of some other operating system is efficient operation of the computer system. The former Operating System exists because they are supposed to make it easier to compute them without them. This view is particularly clear when you look at Operating Systems for small PCs. The latter are used for large , shared , multi user systems. These systems are expensive , so it is desirable to make them as efficient as possible.
These two goals- convenience and efficiency are sometimes contradictory. In past, the efficiency was often more important than convenience. Thus much of the Operating System theory concentrates on optimal use of the computing resources. Operating System also evolved over time.
For example , UNIX started with a keyboard and a printer as its interface. Over time hardware changed and UNIX was ported to new hardware with more user friendly interfaces. Many graphic user interfaces were added , which provide UNIX to be more convenient for user while still concentrate on efficiency.
The designing of an Operating System is a complex task . Designers face many trade offs in the design and implementation, and many people are involved not only in bringing an operating system to fruition but also constantly revising and updating it.
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