Software: the inside story

Computer software determines the types of tasks a computer can help you accomplish. Some software helps you create documents; while other software helps you edit home videos, prepare your tax return or design the floor plan for a new house.

The instructions that tell a computer how to carry out a task are referred to as a computer program. These programs form the software that prepares a computer to do a specific task, such as document production, video editing, graphic design or Web browsing. In popular usage the term “software” refers to one or more computer programs and any additional files that are provided to carry out a specific type of task. Whether it’s on a CD or downloaded from the Web, today’s software is typically composed of many files. You might be surprised by the number of files that are necessary to make software work. At least one of the files included in a software package contains an executable program designed to be launched, or started, by users. On PCs, these programs are stored in files that typically have.exe file extensions and are referred to as “executable files”. Other files supplied with a software package contain programs that are not designed to be run by users. These “support programs” contain instructions for the computer to use in conjunction with the main user-executable file. A support program can be activated by the main program as needed. Support programs often have file extensions such as.dll and.ocx.

In addition to program files, many software packages also include data files. As you might expect, these files contain any data that is necessary for a task, but not supplied by the user, such as Help documentation. The data files supplied with a software package sport files extensions such as.txt,.bmp, and.hlp. (see fig. 2):

The use of a main user-executable file plus several support programs and data files offers a great flexibility and efficiency for software developers. Support programs and data files from existing programs can usually be modified by developers for other programs without changing the main executable file. This modular approach can reduce the time required to create and test the main executable file, which usually contains a long and fairly complex program. This modular approach also allows software developers to reuse their support programs in multiple software products and adapt preprogrammed support modules for use in their own software. Modular programming techniques are of interest mainly to people who create computer programs; however these techniques affect the process of installing and uninstalling software. It is important, therefore, to remember that computer software consists of many files that contain user-executable programs, support programs, and data.

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