Defining an Operating System

Chapter:Chapter 01 – What is an Operating System and Why is it Important?
Subsection: 04. Introduction to Operating Systems
Document Number:01
Topic: Defining an Operating System
Date Composed: 10-27-96 01:32:22 PM Date Modified: 12-29-96 01:37:20 PM

The most important single choice you will make concerning your computer is that of the operating system which will create a useful tool out of it. Computers have no ability to do anything without software. If you turn on a computer which has no software program, it simply generates revenue for the electric company in return for adding a little heat to the room. There are far less expensive ways to heat a room.

The operating system is the first level of software which allows your computer to perform useful work.

Understanding the role of the operating system is key to making informed decisions about your computer. This chapter defines the operating system in terms of its role in your computer. It also discusses the major PC operating systems which are available today and tells you why OS/2 is the best one for a business environment.

Defining the Operating System

Every computer requires an operating system. The operating system performs many critical functions which, in turn, allows the computer to perform useful work.

Figure 1-1: A Typical Computer System From the User’s Viewpoint

To understand the need for an operating system, it is necessary to understand a little about the structure of the hardware which comprises a computer system. The microprocessor which is located in the system unit is the brains of the system. It is the part of the computer which is responsible for executing each of the instructions specified by the software application program. The keyboard is used for input to the computer, and printers and displays can be used for output. Random Access Memory (RAM) is used to store data and programs while they are being actively used by the computer. Programs and data cannot be used by the computer unless they are stored in RAM. RAM is volatile memory; that is, the data stored in RAM is lost if the computer is turned off. Diskettes and fixed disks are magnetic media used for long term storage of data and programs. Magnetic media is nonvolatile; the data stored on a disk remains even when power is removed from the computer.

Figure 1-2: Internal Components of the System Unit

All of these pieces of the computer must work together. Data must be gotten into the computer and moved about between the various components. Programs must be loaded from long term storage on the hard drive into RAM where they can be executed. Processor time needs to be allocated between running applications. Access to the hardware components of the computer such as RAM, disk drives, and printers by application programs must be managed. It is the task of the operating system to provide these functions. The operating system manages the operation of the computer and of the application software which runs on the computer.

A simple definition of an operating system is that it is a program, much like any other program; it is different only in that its function is to manage the movement of data in the computer; it also manages access to the hardware devices of the computer by application programs. In addition, an operating system provides at least some minimal system utility programs for managing various aspects of the system such as the hard drive and memory. These utility programs perform functions like deleting files, copying files from one place to another, establishing serial and parallel port parameters, and setting display resolution.