COS: We can't do without it
We have talked about Windows XP and Linux in the past, but this week I
thought of talking about Computer Operating Systems in general. The operating
system defines our computing experience. It's the first thing we see when
we turn on the computer, and the last thing we see before shutting it down.
It's the software that enables all the programs we use. The operating system
organizes and controls the hardware on our machines, yet most users can't
say with any certainty precisely what it is that the operating system does.
We'll tell you what a piece of software must do for that to be called an
operating system, and show you how the operating system works.
It's should be clear that not all computers have operating systems.
Your calculator, for example, doesn't need an operating system. It has
one set of relatively simple tasks to perform, very simple input and output
methods (a keypad and an LCD screen), and simple, never-changing hardware
to control. Instead, the calculator simply runs a single program all the
For computer systems that go beyond the complexity of calculators, an
operating system is the key to greater operating efficiency and easier
application development. All desktop computers have operating systems.
The most common are the Windows, UNIX and Macintosh operating systems.
There are hundreds of other operating systems available that serve specialized
At the simplest level, an operating system does two things: It manages
the hardware and software resources of the computer system. These resources
include such things as the processor, memory, disk space, etc. On the other
hand it provides a stable, consistent way for applications to deal with
the hardware without having to know all the details of the hardware.Managing
the hardware and software resources is very important, as various programs
and input methods compete for processing (CPU) time and demand memory,
storage and input/output (I/O) bandwidth for their own purposes. The operating
system makes sure that each application gets the necessary resources managing
the limited capacity of the system as efficiently as possible.The second
task, providing a consistent application interface, is important if there
is to be more than one type of computer using the operating system, or
if the hardware making up the computer is ever open to change. An application
program interface (API) allows a software developer to write an application
on one computer and to know that it will run on another computer of the
same type, even if the amount of memory or the quantity of storage is different
on the two machines. Even if a computer is unique, an operating system
ensures that applications continue to run when hardware upgrades and updates
occur, because the operating system and not the application is charged
with managing the hardware and the distribution of its resources. Windows
98 is a great example of the flexibility an operating system provides.
It runs on hardware from thousands of vendors. It can accommodate thousands
of different peripherals in any possible combination.Within the family
of operating systems, there are four types, categorized based on the types
of computers they control and the sort of applications they support. The
broad categories are: Real-time operating systems (RTOS) - they are used
to control machinery, scientific instruments and industrial systems. They
have very little user-interface capability, and no end-user utilities,
since the system will be a "sealed box" when delivered for use. A very
important part of an RTOS is managing the resources of the computer so
that a particular operation executes in precisely the same amount of time
every time it occurs. In a complex machine, having a part move more quickly
just because system resources are available may be just as catastrophic
as having it not move at all because the system is busy.
Single-user, single task - As the name implies, this operating system
is designed to manage the computer so that one user can effectively do
one thing at a time. The Palm OS for Palm handheld computers is a good
example of a modern single-user, single-task operating system. Single-user,
multi-tasking - This is the type of operating system most people use on
their desktop and laptop computers today. Windows and the MacOS are both
examples of operating systems that will let a single user have several
programs in operation at the same time. For example, it's entirely possible
for a Windows user to be writing a note in a word processor while downloading
a file from the Internet while printing the text of an e-mail message.
Multi-user - A multi-tasking operating system allows many different
users to take advantage of the computer's resources simultaneously. The
operating system must make sure that the requirements of the various users
are balanced, and that each of the programs they are using has sufficient
and separate resources so that a problem with one user doesn't affect the
entire community of users. Unix, VMS, and mainframe operating systems,
such as MVS, are examples of multi-user operating systems.It's important
to differentiate here between multi-user operating systems and single-user
operating systems that support networking. Windows 2000 and Novell Netware
can each support hundreds or thousands of networked users, but the operating
systems themselves aren't true multi-user operating systems. The system
administrator is the only "user" for Windows 2000 or Netware. The network
support and all the remote user logins the network enables are, in the
overall plan of the operating system, a program being run by the administrative
Now that we know the different types of operating systems and their
functions, next time we will look into what happens when you turn on the
power switch of your computer. So until then, celebrate life everyone!