1. Nat 4/5 Computing Science Software
Computer Systems
Nat 4/5 Computing Science
Software

2. Lesson Aims By the end of this lesson: All pupils will be able to:
Describe what an operating system is
Describe the functions of an operating system
National 5 pupils will be able to:
Describe a web browser
Describe what an application program is
Describe some utility programs

3. Nat 4/5
Types of software
Operating Systems - controls the computer and devices that are attached to it
Web browsers – display web pages
Applications - performs a particular task e.g. word processing or desktop publishing
Utility programs – useful programs

4. Operating Systems There are many others
Nat 4/5
Operating Systems
An operating system is software that controls the operation of the computer
Two of the more popular operating systems used at present are
Microsoft® Windows
Apple® OSX
There are many others

5. Booting-up
When computer is switched on part of the operating system called the bootstrap loader (in ROM) is run
This loads the rest of the operating system from disk and puts it into RAM
The operating system runs all the time when the computer is on

6. Platform
“Platform” means hardware and software that make up a computer
2 popular platforms:-
Mac platform – runs Mac Os operating system
PC Platform – runs Windows operating system
Single platform software runs on 1 platform
Dual platform software runs on both platforms

7. Software/system requirements
When buying application software check the system requirements to ensure it runs on your platform

8. Photoshop CC 2014 system requirements

9. Functions of an operating system
Nat 5
Functions of an operating system
Provide a Human Computer Interface (HCI)
Handles input and output
Memory Management
File management
Error reporting
Manages the security of the computer – manages users and passwords

10. Operating System Functions: Provide a Human Computer Interface (HCI)
Nat 5
Operating System Functions: Provide a Human Computer Interface (HCI)
Lets the user give commands and see the effect of their commands
Graphical User Interface – icons
Command line interface - user types commands

11. Functions of an Operating System – Handles Input and Output
Nat 5
Functions of an Operating System – Handles Input and Output
Sends and receives data to and from peripherals

12. Functions of an Operating System – Memory Management
Nat 5
Functions of an Operating System – Memory Management
Decides which locations in RAM each program is loaded into

13. Functions of an Operating System – Memory Management
Nat 5
Functions of an Operating System – Memory Management
Allocates space in memory for programs & data
Allows multi-tasking – more than 1 program in memory at a time that user switches between
Prevents operating system in RAM being overwritten by user’s programs and data – memory protection

14. Functions - File Management
Nat 5
Functions - File Management
Decides where files are saved on backing storage and finds files when they to be loaded

15. Functions - File Management
Organises files in hierarchical filing system
Allows a logical arrangement of files
Same filename can be used in different directories
Directory
Sub-directory
File

16. Functions of an Operating System – Error Reporting
Nat 4/5
Functions of an Operating System – Error Reporting
Provides useful feedback to users when errors occur

17. Operating System Summary
Nat 4/5
Operating System Summary
The Operating System (OS) is a program which manages the computer and the peripherals attached to it
The functions of an OS are:
Provide a Human Computer Interface
Handle Input and Output
File Management
Memory management
Error Reporting
Provides security

18. Questions What is an operating system? What is a platform?
Where is the bootstrap loader stored?
When does the bootstrap loader run?
Describe what the bootstrap loader does.
When does the operating system program run?

19. More questions What is a dual platform application?
Why is it important to check system requirements when buying an application?
State the function of the operating system that:-
Decides where each program is stored in RAM
Locates a file on disk when it is to be loaded
Allows the user to give commands

20. Pupil Task
Pick three different operating systems and find the following:
Its latest version (name or Number)
Three features of the OS
One recent news article about the OS (recent being in the last year)

21. Web browsers Lets user browse the World Wide Web
Loads web pages from web servers
Displays web pages on user’s computer
Examples are:-
Internet Explorer
Mozilla Firefox
Safari
Google Chrome

22. Web browsers Html file that browser loads from web server
Web page that browser displays

23. Applications Software
Nat 5
Applications Software
Programs that are designed to do a particular task
E.g. Microsoft Word, games, Photoshop

24. Utility programs Perform everyday tasks
Either part of the operating system or separate programs
E.g.:-
Emulator – enables your computer to run software that was created for a different platform
Virus checker – detects and removes viruses
Defragmenter – tidies up hard disk
Backup – creates backup copy of files

25. Even more utility programs!
Converters, compressors & expanders
Installers/uninstallers – copy program to hard disk or remove it
Printer drivers – enable the computer to send the correct signals to the printer
filter & web filters

26. Web browsers and utility program questions
Describe the function of a web browser
Name 3 utility programs that you have used
Why would you use an emulator?
Why would you use a compressor?
Which utility program is essential if your computer is connected to the internet?