Section 1.2
Introduction To Computing
1.2 Computer Software
Software is a set of instructions that will make a computer perform a task.
There are four types of software:
- Applications
- Operating Systems
- Utility Programs
- Programming Languages
1.2.1 Applications Software
These packages enable people to carry out different tasks on a computer.
General Purpose Software
- Word Processing
- Spreadsheets
- Desktop Publishing
- Databases
- Graphics
- Computer Aided Design
- Telecommunications
- Multimedia Authoring
- Expert Systems
Special Purpose
Special purpose applications software is used widely but only for a small
number of people in any given field. For example:
- Theatre Booking
- Stock Control
- Insurance Quotes
- EPOS (if not firmware)
- Dentist/GP Appointment Systems
1.2.2 Programming Languages
Before the 1950s there was no software to help programmers write programs.
All computers process instructions using machine code. This is called low-level
programming because it uses many simple calculations in binary.
A big development in computing was the introduction of assembly language where
the binary machine code was represented by two or three letters. Assembly language
was the first programming language.
Each program requires its own translation program. This can be an interpreter or
a compiler. An interpretor translates code instruction by instruction and is
therefore quite slow. A compiler translates a source code file into machine code,
saving it as a file taht can be executed later.
1.2.3 Operating Systems
The operating system always runs in the background allowing the system to perform
such tasks as:
- loading and running applications
- managing the position of files on a storage device
- multitasking management
There are two types of operating systems:
- Graphical User Interface Systems which use WIMP (Windows,
Icons, Menus & Pointers) principles to manipulate files and control the
system.
- Text User Interface Systems which require the user to
type commands in.
1.2.4 Utility Programs
Utility programs have no distinct result - they merely help the user to acheive
a result. They are usually very closely linked to the operating system.
Examples of such programs:
- Screen Savers
- Disk Defraggmenters
- Anti-virus Software
- Compression & Partitioning Software
