Software, Characteristics and Qualities of Software, Types of Softwares

1. SOFTWARE
Software refers to a program that makes the computer to do something
meaningful. It is the planned, step by step instructions required to turn data into
information.
 Nature of software:
Software is a logical entity rather than a physical system entity. Software
characteristics are quite different from that of hardware.
The characteristics of software are as under:
i) Software is engineered and not manufactured:
Software is developed or engineered. It is not manufactured in the traditional
sense, to engineer a software product high quality is to be achieved through
good design after critical analysis by people (users, management and
development team).
ii) Software does not wear out:
Software does not wear out due to age but it deteriorates. Whereas in case of
hardware, it exhibits relatively high failure rates due to affects of dust, vibration
abuse, temperature extremes.
iii) Software is a differentiator:
In case of hardware, the design engineer draws the digital circuitry after doing
the basis analysis and then results in lots of hardware products.
Software products most often are developed in view of the customised customer
requirements and systems tends to customer specific.
 Qualities of software:
i) Correctness: A program is functionally correct if it behaves according to the
specification of the functions it should provide (called functional requirements
specifications).
ii) Reliability: Informally, software is reliable if the user can depend on it .It is
also defined as reliability in terms of stastical behaviour i.e. the probability that
the software will operate as expected over a specified time interval .

2. iii) Robustness: A program is robust if it behaves’ reasonably’ ,even in
circumstances that were not anticipated in the requirements
specifications.Eg.when it encounters incorrect input data or some hardware
malfunction (a disc crash).
iv) Interoperability: It refers to the ability of a system to co-exist, and co-
operate with other systems.
v) Timeliness: It is process-related quality that refers to the ability to deliver a
product on time. Timeliness requires careful scheduling, accurate estimation of
work etc.
vi) Repairability: A software system is repairable if it allows the correction of
its defects.In many engineering products; repairability is a major design goal.
vii) Performance: It is important because it affects the usability of the system.
If a software system is too slow, it reduces the productivity of the users,
possibly to the point of not meeting their needs.
viii) Evolvability: Like other engineering products, software products are
modified over time to provide new functions or to exchange existing functions.
The fact that software is so malleable makes modifications extremely easy to
apply to an implementation.
 Types of Software’s:
The software’s used by the computer can be classified into two categories.
i) System software
ii) Application software

3. 1) System software: It is a set of one or more programs that are basically
designed to control the operation of a computer system. It is also known as
system packages. This system software allows the users to communicate with
the computer and write or develop their own programs.
Systems software provide support to the following
a) Running and development of other software’s
b) Communicating with peripheral devices like printers, disc and tape devices
etc.
c) Monitoring the use of various hardware resources such as CPU, Memory etc.
 Types of system software’s:
i) System control programs: It controls the use of hardware, software and data
resources of the system.
Eg.Operating System
ii) System support programs: It supports the operations, management and the
users of a computer system by providing a variety of support services. Those are
a) System Utilities like sorting records, copying disc files into magnetic
tape for backup, restore deleted files etc.
b) System performance monitor is a utility used to track a range of
processes and give a real time graphical display of the results.
c) System security monitors are programs that monitor the use of
computer system to protect computer and its resources from unauthorised use,
fraud or destruction.
2) Application Software: It is also known as application packages. It is the set
of one or more programs designed to carry out the operations for a specified
applications.
Eg. Every month a payroll package produces the pay slip for the workers of an
organisation.

4.  Types of Application Softwares:
i) Proprietary software: This application software addresses a specific
business need for a company. This type of software may be developed in- house
by the organisations information systems personnel.
ii) Off-the- shelf software: This application software can be purchased, leased,
or rented from a vendor that develops programs and sells them to many
organisations.
Personnel application software: These packages include spreadsheet
software’s, database software, word processors, desktop publishing and graphic
packages etc.