Topic 1.2. Types of Software

Software

• Is the general term for any program or set of instructions used to make a computer perform a task.
• Every processor, whether it is inside a mainframe computer, individual workstation or pocket camera, has to be given instructions in the form of a program before it can do anything at all.

Categories of Software:

1) General purpose applications software

2) Special purpose applications software

3) Programming languages, compilers and interpreters

4) Operating systems

5) Utility programs

GENERAL PURPOSE APPLICATIONS SOFTWARE

This category includes the common software packages that are found on most desktop computers most of which you will almost certainly use during your course. Examples:

• Word processing software (e.g. Word, WordPerfect) for producing and saving well laid out documents such as business letters, technical manuals, books, memos and reports.
• Desktop publishing software (e.g. PageMaker, Ventura, FrameMaker, PagePlus) for producing among other things like magazines, advertisements, newsletters and books.
• Spreadsheet Packages (e.g. MS Excel, Lotus 123, SuperCalc) for working with numbers, producing accounts and tabulated numerical information of all types.
• Database Packages (e.g. MS Access, Paradox, FoxPro) for information storage and retrieval. Databases are used in thousands of different applications from airline booking systems, mail order and invoicing systems to keeping tabs on distances flown racing pigeons.
• Graphics Packages (e.g. Paint, PaintBrush, CorelDraw) for producing artwork, 3 dimensional images, special textual effects.
• Computer-aided-design Packages (e.g. Turbo CAD, AutoCAD) for producing accurate engineering or architectural drawings.
• Multimedia Authoring Tools (e.g. Authorwave, Macromedia Director) which combine text, graphics, animation, sound and video for presentations, games, interactive tutorials etc.
• Telecommunications software (e.g. Internet Solution) which enables you to send and receive data over a wide area network via a modem, access the internet, send and receive electronic mail, browse the worldwide web.
• Expert Systems Software (e.g. Crystal, ELSIE) which can be programmed with the facts and rules about a certain 'domain' or field of knowledge such as geological data around known oil fields The system can then be used to predict the likelihood of finding oil in a new location, given its geological profile.

SPECIAL PURPOSE APPLICATION SOFTWARE

- When an organisation wants to computerise some aspect of its business, it is often possible to buy an 'off the shelf' package to do more or less exactly what it wants.

- There are literally thousands of specialist applications readily available to perform such tasks for example:

• keeping business accounts
• stock control
• payroll
• general practice management and appointments
• theater booking

- The alternative to buying one of these packages is either to buy a database package and build a customised application to suit your exact requirements; OR write a suite of programs using a language such as PASCAL or C to perform the required tasks.

PROGRAMMING LANGUAGES

• All computers process instructions using machine code, which uses codes to represent basic operations such as load, move, add, subtract, compare and so on.
• Early programmers in 1940s and 1950s had to program using these numeric codes, a slow and tedious process.
• Later, programs were written which translated statements such as 'Add 1 to counter' into machine code so that programmers could write in something more closely resembling English, which was easier to learn, faster and quicker to debug.
• There are 100s of programming 'languages' and each of these languages comes with its own 'translation' program (one of two types: compilers and interpreter) which will take the code you write and turn it into machine executable form.
• Programmers who invent computer languages and write compilers or interpreters for them are called as system programmers.
• Bill Gates is the head of Microsoft who invented BASIC in 1971.

OPERATING SYSTEMS

• While you are using a computer to write a program or do some word processing, the operating system is working away in the background, following instructions that determine where in memory your program or document is stored, where on disk it will be saved and what to do if for example you press <Ctrl><Break> to interrupt the execution of your program.
• No computer can operate without an operating system.
• The essential parts of the operating system are loaded from disk into memory as soon as you switch your computer on. Other parts of the operating system (such as some utility programs) will be copied into memory when required.
• MS-DOS (Microsoft Disk Operating System) is a character-based operating system.
• The user has to communicate with the operating system via a command interface, which means you have to know exactly what to type to get it to do what you want, like display a list of which files are in a particular directory on your disk.

UTILITY PROGRAMS

• Utility programs perform common tasks such as formatting disks, copying and deleting files or repairing damaged files.
• Many utility programs are supplied with the operating system and can be called directly from it.
• Other utility programs can be purchased from a number of software manufacturers, such as

        - PC Tools: a collection of utilities for PC system maintenance, management and protection.

        - Dr Solomon's Anti-Virus Toolkit: a virus detection and protection system.

        - After DarkScreenSaver: screen displays that appear when you leave the computer alone for a few minutes.

Resources:

(1) P M Heatcote, [A level Computing, 3rd. edition], Ashford Colour Press Ltd, Gosport, Hants, 1996.

(2) Janel D. White-Taylor, [http://seamonkey.ed.asu.edu/emc300/software/types.html], Arizona State University, 1995.