Computers today. Гурьянова В.И. - 25 стр.

      3) to compare OSs;
      4) to show details about OS;
      5) to describe purpose of OS.
      5. Summarize the text according to your plan.


                                    System software
      The concept of an operating system (abbreviated OS) is a difficult one to
explain. In essence, an operating system is a program which supervises a com-
puter, and which is necessary to make the computer run efficiently enough to be
of practical use. The actual computer machinery (the “hardware”) and the pro-
grams used in individual application (the “application software”) are not enough
in themselves to make the computer run easily. In order for an instruction to be
transmitted to the computer and for the computer to carry out that instruction
well, a program which supervises the computer is also needed. A good analogy
is a company or government department in which it is not enough to have only
the people who do the actual work; administrators to run the organization are al-
so needed.
      There are different types of operating systems for different purposes and
computer systems. Many of them pretend to have the following characteristics:
      1. Global.
      2. Aimed at multiple users.
      3. Interactive.
      4. Time sharing.
      5. Multi-programming.
      Let us now examine what these terms mean.
      1. A global operating system is not intended only for one specialized use,
but can be used in many different applications. On one occasion it might be used
for office automation, on another occasion for controlling experimental appara-
tus, and on still another occasion for developing new programs.
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