SAD-Software Industry

Software has become an industry in itself. We will define the types and characteristics of software for system development.

Types of software

Software is classified according to whether it performs internal computer functions or allows use of the computer for problem solving. The former is called systems software- programs designed to control system operations . The latter is called applications program, which perform user-oriented functions. Within this classification we have 2 groups :

• Cross industry applications software, such as accounts receivable and payroll calculations
• Industry specific software, such as a safe deposit tracking system, hospital billing system, or airline reservation system.

In general software can have one or more of the following attributes

Concurrence of operation – Software allows simultaneous activities to take place in a computer run. For ex, keying in data on the terminal takes place while the system is reading in data from disk and the central processor is operating on a separate activity.

Resource and information sharing – Different programs share the same hardware resource. Different users may use various programs, or different programs use a centralized database. This implies multiple interfaces of a system with the outside world.

Modularity – Software consists of segments connected in various ways , partly due to the separate functions they perform

Multiplexed operation – Some software systems rotate the use of a resource such as a input/output device, among different users, while each user has the impression of being the sole user of the system.