Types of software

Since the computer knows only what the program tells it, the program must tell it everything it needs to know about the process being executed or the problem being solved. This requires a step-by-step approach, developed by the programmer in such a way that no steps are assumed to be known by the com­puter. These steps are then converted into a program that is written in a com­puter language. There are many (well over 100) computer languages that can be used to communicate with a computer. Each computer language, like a human language, has its own vocabulary and grammatical rules, but most share a similar logical approach to communication with the computer. Commonly used lan­guages are BASIC, COBOL, FORTRAN, Pascal, LOGO, and C.

An ever-growing number of software packages are available to the computer user. In fact, nobody can make even a reasonable estimate of the number of programs that are available. With this wide variety of software, beginning users can become confused about what they need to purchase. To unravel all of the talk about software packages, we must first categorize the types of software that are used in a computer. The three major categories are systems software, utility software, and applications software. Usually, all three of these software types are at work in the computer at the same time, each serving a different purpose.

The first of these, systems software, is extremely important because it controls the operations of the other two types of software as well as controlling the computer itself. The most important part of systems software is the oper­ating system, which directs the operations of the computer.

Utility software controls day-to-day "housekeeping" operations. These include such operations as making copies of information, displaying a list of user information, and using different computer languages on a computer.

Applications software constitutes the greatest proportion of the software used on computers. This software performs the specialized tasks that we hear so much about, including calculating payrolls, guiding space shuttles, doing word processing or home budgeting, and playing games.

We can view these three types of software and the way they work con­currently in the computer as an "onion". The outer layer of the onion is applications software, which is evident to the user since it is the software that actually performs the desired task. Underneath the applications software is the utility software, which is invisible to the user until a housekeep­ing chore—such as copying information—is required. Finally, at the core of our "onion" is the systems software, which is almost completely invisible to the user.

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