Computer studies

1. COMPUTER SOFTWARE

2. GENERAL OBJECTIVES
After studying this chapter, you should be able to:
Define a computer software.
Correctly classify software into system and application.
Compare and contrast software into system and application.
Understand the qualities of a good software
Define an operating system.
Understand the main computer user interfaces
State and explain the types of Operating System.
State and explain the functions of Operating System.

3. INTRODUCTION
It is the collection of computer programs and
related data that provide the instructions
telling a computer what to do.

4. CATEGORIES OF SOFTWARE
There are generally two broad types of software namely, systems
software and application software. The relationship between them is
shown in the diagram below.
Application software
System software
Hardware

5. SYSTEM SOFTWARE
System software controls and coordinates computer resources (hardware
and software) so that the computer user and applications can smoothly
interact.
System software include:
Operating Systems
utility programs
device drivers
 programming languages.
BIOS (Basic Input/output System)

6. SYSTEM SOFTWARE CONT..
Operating System
An operating system is a system software that
manages the computer’s resources both hardware
and software, and provides an interface through
which a human can interact with the computer.
Examples of OS include: Windows (XP, vista, 7, 8, 8.1,
10), UNIX, Linux, Mac OS X, MS-DOS.

7. SYSTEM SOFTWARE CONT..
OPERATING SYSTEM EXAMPLES

8. SYSTEM SOFTWARE CONT..
Utility Programs
Utility software is software designed to help analyze,
configure, optimize and maintain the computer. Examples
of utility software include:
 disk defragmenters
 backup utilities
 disk compression utilities
 disk cleaners
 file managers
 anti-virus.

9. SYSTEM SOFTWARE CONT..
UTILITY PROGRAMS EXAMPLES

10. SYSTEM SOFTWARE CONT…
EXAMPLES OF UTILITY SOFTWARE AND FUNCTION
UTILITY SOFTWARE FUNCTION
Disk
defragmenters
Detect computer files whose contents are broken across several locations
on the hard disk, and move the fragments to one location to increase
efficiency.
Disk cleaners Find files that are unnecessary to computer operation, or take up
considerable amounts of space. Disk cleaners help users decide what to
delete when their hard disk is full.
Backup utilities make copies of all information stored on a disk, and restore either the
entire disk (e.g. in an event of disk failure) or selected files (e.g. in an
event of accidental deletion).

11. SYSTEM SOFTWARE CONT..
EXAMPLES OF UTILITY SOFTWARE AND FUNCTION
UTILITY SOFTWARE
FUNCTION
Disk compression
utilities
Reduce the space that a file takes up on disk, increasing the
capacity of the disk.
File managers Provide a convenient method of performing routine data
management tasks, such as deleting, renaming, moving, copying,
merging, generating and modifying data sets.
Disk partition
utilities
Divide an individual drive into multiple logical drives, each with its own
file system which can be mounted by the operating system and treated
as an individual drive.
Virus checkers Prevent, detect, and remove malware.

12. SYSTEM SOFTWARE CONT..
Programming Software
Programming software usually provides tools to assist a programmer in
writing computer programs, and software using different programming
languages.
These tools include:
Compilers
Interpreters
Assembler
Debuggers
Linkers
Loader

13. SYSTEM SOFTWARE CONT..
Programming
Software
ROLE
Compilers Translate instructions written in a high-level language into machine
language instructions. A compiler reads the whole source code at once
before reporting errors.
Interpreters Translates and executes instructions written in a high-level language into
machine language instructions one line at a time.
Assembler An assembler translates assembly language programs into
machine code.
Debuggers Detect and remove bugs. A bug is an error in a computer
program
Linkers Link parts of a computer program together.
Loader Loader is a part of operating system and is responsible for
loading executable files into memory and execute them.

14. SYSTEM SOFTWARE CONT..
BIOS (Basic Input/output System)
BIOS or system BIOS is software stored on a non-volatile ROM chip
built into the system on the motherboard.
It is the first code that is run by the PC when powered on (boot
firmware).

15. APPLICATION SOFTWARE
Application software direct the computer to perform one or more
specific tasks for the end user. They are designed to do the jobs that the
user wants such as word processing, spreadsheets, database, and
graphics.

16. APPLICATION SOFTWARE CONT…
APPLICATION SOFTWARE EXAMPLES

17. APPLICATION SOFTWARE CONT…
CATEGORIES OF APPLICATION SOFTWARE
Application software include a variety of programs that can be
divided into three categories:
 general-purpose applications
 special purpose applications
 tailor-made (bespoke) applications.

18. APPLICATION SOFTWARE CONT…
GENERAL PURPOSE APPLICATION SOFTWARE
General purpose application software or generic
software is software designed to solve a wide range
of related tasks.
They are always available off-the-shelf ie. That is,
they can be bought from the market.

19. APPLICATION SOFTWARE CONT…
GENERAL PURPOSE APPLICATION SOFTWARE EXAMPLES
GENERAL PURPOSE
APPLICATION SOFTWARE
TYPES OF PROCESSING EXAMPLES
Database Software Organize and access large amounts of data. MS-Access, Oracle, Dbase,
FileMaker
Spreadsheet Software work with numbers, calcalations and graphs. MS Excel, Lotus 1-2-3, Quattro
Pro, Apple Numbers
Word Processing Software Create mainly text (Letters, term papers) MS Word, WordPerfect, WordPad,
NotePad
Presentation Software Build a slide presentation MS PowerPoint,
HyperStudio, Digital Chisel
Desktop Publishing Software generate layouts and produce quality text and
images comparable to traditional printing
MS Publisher, Adobe PageMaker,
Quark Express
Graphics Software Work with photos and arts. Corel Draw, Adobe
Photoshop

20. APPLICATION SOFTWARE CONT…
Special purpose Applications
Special purpose applications are software designed or written for a particular
situation or specific task.
They are generally not available in shops unlike generic software and they often
have to be purchased directly from the software manufacturer or a specialist firm.
Special purpose Applications Examples
 Traffic control
 Payroll and time keeping
 Aircraft navigation
 Weather forecasting

21. APPLICATION SOFTWARE CONT…
Bespoke (tailor-made) applications
Bespoke application software is software written specifically for
the needs of a user or company. It is "tailored" to their exact
requirements.

22. ATTRIBUTES OF SOFTWARE
Characteristics Descriptions
Portability It is the ability for software to operate on multiple platforms. For example,
will an application running in Windows run in GNU Linux.
Reliability Reliability refers to the ability for software to perform its intended functions
and operations in an environment without experiencing failure.
Usability Usability is the measure of software’s potential to accomplish the goals of
the user.
Performance Performance tells us of how well the required features of software can
perform assigned tasks.
Availability Availability refers to the ratio of time software is functional to the total time
it is required to function. Sometimes, it is expressed in qualitative terms,
indicating the extent to which software can work.
Efficiency Efficiency refers to how fast software will carry out a given task or a given set
of tasks. It is often measured in time.

23. OPERATING SYSTEM
An OS is a system software that manages the
hardware and software resources of a computer,
and serves as interface between the computer
user and the computer.

24. COMPUTER USER INTERFACES
OPERATING SYSTEM cont…
Computer user interface also referred to as Human-Computer
Interface (HCI), is the term used to describe the
communication between humans and computer systems.

25. OPERATING SYSTEM cont…
Command Line Interface is a user interface where the user
types instructions through the a command prompt for the
computer to carry out. E.g.MS-DOS and OS/2.
Command Line Interface (CLI)

26. OPERATING SYSTEM cont…
Graphical User Interface
GUI is a user interface that uses computer graphics to
ease the user’s operation. Commands are issued by
using a pointing device to point and click on icons,
buttons, menus and lists on the screen. Examples of
GUI are MS Windows, Apple Macintosh and Linux OS.

27. OPERATING SYSTEM cont…
Menu Driven Interface
It is a user interface that allows the user to make use of
features like menus, pointers or arrow keys to communicate
with the computer. The user chooses an item from a displayed
list. They are also called graphical character based user
interface. Example, Mobile phones.

28. OPERATING SYSTEM cont…
CLASSIFICATION OF OPERATING SYSTEMS
Multiprogramming system
Multi-tasking system
Multi-user system
Multi-processing system
Multi-threading systems

29. OPERATING SYSTEM cont…
TYPES OF OPERATING SYSTEMS
Batch Processing Systems
Real Time Operating Systems
Network Operating Systems
 Embedded Operating Systems

30. OPERATING SYSTEM cont…
Functions Of OS
Resource Management
Memory Management
Processor Management:
Task Management
File management
Providing a user interface

31. Review Questions
1. What is a computer software?
2. Explain what is meant by off-the-shelf.
3. State and explain the following qualities of a
good software.
4. Define and give an example of an integrated
software.