Purchasing an information system: application software.

• Author: Sandlin, Roscoe
• Position: Tips for local government officials

Editor's note: The following is reprinted from Manager's Guide to Purchasing an Information System, by Roscoe Sandlin and published in 1996 by the International City/County Management Association (ICMA). The guide is prepared for the local government manager who has been called upon to make decisions about the acquisition and implementation of an information system. From Chapter 2, "What Do You Really Need to Know?," comes this excerpt about application software.

Application software is what does the job - it applies computer technology to the task at hand. Payroll is an application. So are accounts payable, water billing, and voter registration. Application software controls what you see on the screen. Your technical staff (if you have technical staff) will deal with all the other components - hardware, operating system, and networking.

Application software is essentially a set of instructions written in a programming language that is interpreted by the operating system. The operating system then tells the central processing unit what to do. The most fundamental programming language, Assembler, is somewhat like Morse code, sending a series of eight on-off electrical signals (bits) to represent a single character (byte). Other languages are categorized in terms of how far they can remove the programmer from the tedious task of writing out all those ones and zeroes (1 is on, 0 is off). They are usually discussed in terms of "generations." Cobol and Basic are third-generation languages. Companies such as Sybase and Informix, among others, produce fourth-generation languages (4GL), and there are a number of lesser-known proprietary 4GL products.

What you need to know about programming languages is that, generally speaking, a 4GL should be easier and cheaper to enhance and maintain. Language will be one factor in your evaluation of the software but only one factor. Most important, a language is not an application. Applications are written in programming languages. So don't buy a 4GL thinking it will do your payroll for you.

The application software is by far the most important component of an information system, and it should be the starting point in your purchase. It is the software that enables you to achieve the strategic goals you have so painstakingly defined. The other pieces - hardware, operating system, and network - support the application software.

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