It is nice to work on a computer. With a light movement of the mouse
I can make it do what I want: launch a program, connect to Internet,
print a report and much more. I may well become proud that everything
happens according to my plan and my will, but my IT-experience prevents
me from that feeling. I have to pay tribute to someone behind the
scenes, who is handling the necessary tasks for each of my
mouse-clicks. It is the Operating System.
What is the
operating system? This is the main program that controls a computer.
Since it is very complex and consists of a huge set of interrelated
programs, it is called a system. And as this system operates with all
other parts of the computer, it is called the Operating System,
abbreviated as OS.
The operating system is a critical
part of the computer. A computer without an operating system would be a
simple shell of possibilities and no more. After power on that computer
typically issues diagnostic messages, and then displays a request to
insert a disc with the OS. This is the end of its mission, and nothing
more possible.
The computer becomes fully functional
only after the installation of an operating system. Typically,
computers come preloaded with the operating system. Personal computers
come with Microsoft Windows, Macintosh computers come with Mac OS X,
and IBM mainframes AS/400 come with OS/400. Many corporate servers use
Linux or UNIX operating systems. When we buy a computer, usually
everything is installed, and we only have to turn it on.
When
we turn on the power to a computer, first runs a set of instructions
that stored in the computer’s permanent memory. This code checks the
system hardware to make sure that everything is working properly. This
procedure is called power-on-self-test (POST). It checks the processor,
memory and basic input / output system (BIOS) for errors and stores the
result in a memory location.
Upon successful
completion of POST, this program will begin to activate the computer's
disk drives. At this stage the program loads the first part of the
operating system, which has a single function: it loads into memory the
remaining part of the operating system and turns control of the
computer over to the operating system. Since then the computer is under
control of the operating system, and we have our familiar desktop where
we usually work.
The operating system is responsible
for translating commands issued with a keyboard and mouse into binary
code (010110101 stuff) to communicate with a set of hardware and
software so that the computer behaves flexibly and predictably. The
tasks of the operating system, in the most general sense, are divided
into six categories:
• Processor management;
• Memory management;
• Device management;
• Storage management;
• Application interface;
• User interface.
There
are many books on operating systems. Various books classify these tasks
in different way, but these six tasks define the basis of nearly all
operating systems.
Thus, only after running of the
operating system, computer revives and becomes obedient. If we compare
the computer with a living creature, the operating system would be the
soul and intelligence of that creature.
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