1. Software, O/S & Interfaces
F451 - AS Computing

2. Hardware and Software Definition Hardware Definition Software
The physical components that make up a computer system. Includes all input, output, storage devices
Definition Software
The computer programs that tell the computer what to do.

3. Layers of software Application Software System software
General purpose
Special purpose
Bespoke
System software
Operating system software
Utility programs
Library programs
Compilers, assemblers and interpreters
Library programs

4. Systems & Application Software
Systems Software controls the operation of the hardware/runs the computer/manages the applications
Applications Software makes the computer do something useful carries out tasks

5. Applications Software
The term applications software refers to all the programs used for a wide variety of purposes
There are three categories:
general purpose
special purpose
bespoke (custom).

6. General purpose software
The term general purpose software refers to applications with a number of common uses:
word processing packages
spreadsheet packages
database packages
presentation packages

7. Special purpose software
Special purpose software is designed to carry out a specific task
It is commonly used by organisations, businesses
Stock control
Payroll systems
Accounting

8. Bespoke (custom) software
The term bespoke software refers to software that is tailor-made rather than bought off-the-shelf.
It may be created in-house or using programmers from a software house.

9. System Software
The term system software refers to the software that is needed to set up and run the computer.
This software is often invisible to the user.
There are four types of system software:
operating system software
utility programs
library programs
compilers, assemblers and interpreters.

10. Operating System Software
The operating system software (OS) is a suite of programs that controls the hardware and software.
It acts as an interface between the user and the computer.

11. Role of Operating Systems
Used to control the hardware of the system and resource management through software like hardware drivers/system software
Used to provide a platform on which applications can run
Deals with issues that the software may have with eg storage of files
Provides a user interface
Allows communication between user & hardware
Has many utility programs used to carry out housekeeping on system

12. Utility Programs
Utility programs are software written to carry out housekeeping tasks on the computer.
Examples include:
spell-checkers
wizards
compression software

13. Compression Software Reduces size of files
Useful when large files are being sent via
The compression means they are sent more quickly
They are decompressed using a decompression algorithm

14. File Handlers Manages data storage/organises data storage
Allows files to be accessed
Allows for deletion/sorting of files

15. Hardware Drivers
Contain the instructions to the OS for using a peripheral e.g.. a printer
Allows control of peripheral by OS
Written in a low level language (assembly)

16. Backup Utility Automatically makes copy of files at regular intervals
Can be set to run a full or incremental backup

17. Library Programs
They are similar to utility programs, although they are essential to the user.
The library program may work alongside many different applications.
An example could be the science department of a university whose users may need mathematical library programs to carry out tasks on scientific data.

18. Compilers, assemblers and interpreters
A program is a series of instructions.
Compilers, assemblers and interpreters are used to turn these instructions into machine code that the computer can carry out the instructions.

19. Different Methods of O/S
Batch Processing
Real Time Processing
Single User
Multi User

20. Batch Processing Commonly used in: Payrolls Banks Billings
Financial Sector

21. Batch Processing Often run during night time/weekends
No need for human to be present
Run in computer downtime when workers have gone home
No need for instant response to inputs
Processes large amounts of data in one go

22. Real Time Processing Data is processed instantly
System responds instantly to changes in input
Automatic Pilots on Airplanes
Computer controlled systems

23. User Interface Computer Mobile Phone ATM Car
The method where the user tells the device what to do and the device responds.
Computer
Mobile Phone
ATM
Car

24. Menu Driven Interface Easy to use Require little technical knowledge
Limited to the options available

25. Graphical User Interface`
Graphical User Interface
Advantages
Commonly used
Easy to learn
Intuitive
Disadvantages
Require more processing power and system resources

26. 4 Features of a Graphical User Interface
Windows
Icons
Menu
Pointers

27. Designing a User Interface
Factors to consider include
Use of sound
Warnings to user
Colours Used
Easy on the eye
Experience of User
CLI can be difficult to master
Platform
GUI requires more processing power

28. Designing a User Interface
Must consider environment when designing an interface – e.g. an office environment or a factory have different level of noise, light.