1. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Topic 3 Software System Software (1) The Operating System

2. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Activity 1 Questions to discuss: What is an operating system? What is the role of an operating system?

3. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Computer Systems and their Importance What is software? Ultimately, it is the programs, their data and any digital documentation that goes with the programs. This is in contrast to hardware, which is the physical devices on which software runs. This topic will look at software, in particular: Learning Objectives: (a)Explain the need for the following functions of an operating system: user interface, memory management, peripheral management, multi-tasking and security. System Software : Operating systems and their utility programs (software which enables computer devices to work with one another) Application Software : Programs such as browsers, word processors and music players (software which allows the user to perform a task).

4. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Computer Systems and their Importance The Operating System The operating system is the most important piece of software on any computer. Without it, no programs will run. This is because an operating system is responsible for controlling / communicating with the computer hardware. It provides a platform on which games, browsers, music players etc, can all work. WHY? Learning Objectives: (a)Explain the need for the following functions of an operating system: user interface, memory management, peripheral management, multi-tasking and security.

5. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Computer Systems and their Importance The Operating System If you were to run an everyday program (e.g. a word processor), without an operating system, nothing would be displayed on the screen, nothing could be sent to the printer, nothing could be typed. This is because application software, does not know how to TALK to hardware devices. However, the operating system does. The operating system can also talk to the application that is running. So when you print a document, the application talks to the OS, which in turn talks to the printer. Learning Objectives: (a)Explain the need for the following functions of an operating system: user interface, memory management, peripheral management, multi-tasking and security. User Application Operating System Hardware

6. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Computer Systems and their Importance The Operating System Learning Objectives: (a)Explain the need for the following functions of an operating system: user interface, memory management, peripheral management, multi-tasking and security. The operating system sits between the user’s applications and the hardware. It enables applications to use the hardware resources.

7. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Computer Systems and their Importance The Kernel The kernel is the heart of the operating system and is responsible for looking after “the most low- level hardware operations”. It is the kernel that applications make use of when they want to operate the computer’s hardware. Learning Objectives: (a)Explain the need for the following functions of an operating system: user interface, memory management, peripheral management, multi-tasking and security. Applications Kernel CPUMemory Devices

8. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Exam Question Practice “Using an example, explain why an Operating System is essential when running applications on a computer.” 4 marks Exam technique: Using an Example Explain 4 Marks

9. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Exam Question Practice “Using an example, explain why an Operating System is essential when running applications on a computer” 4 marks 2 marks for a detailed reason why an operating system is needed to run a program 2 marks for a detailed example of a program’s need for an operating system. Assessment Criteria

10. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Exam Question Practice “Using an example, explain why an Operating System is essential when running applications on a computer” 4 marks The operating system gets the applications and hardware working together. The operating system would pass instructions from a music player application to the speakers to allow sound to play. 1 1 A 2 mark answer

11. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Exam Question Practice “Using an example, explain why an Operating System is essential when running applications on a computer” 4 marks Without an operating system, applications would not be able to communicate with the computer’s hardware. The operating system bridges the gap. It gets the application and hardware working together. Example: Without an operating system, a music player would not be able to talk to the speakers and therefore would not play any sound. The operating system would pass instructions from the application to the speakers to allow sound to play. 1 1 1 1 A 4 mark answer

12. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Computer Systems and their Importance The Operating System Ultimately, the operating system provides 5 major roles: -Memory Management -Peripheral Management -Multi-Tasking -Security -User Interface Learning Objectives: (a)Explain the need for the following functions of an operating system: user interface, memory management, peripheral management, multi-tasking and security.

13. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Activity 3 Around the room are 18 questions. In groups of 3 you will be given a booklet of information about the 5 functions of the operating system. In your groups you need to write ( in full sentences ) the answers to each of the 18 questions. The group with the best quality 18 answers will win. After your team have shown me all their answers, each of you must create a revision card (spider diagram) summarising each function. Questions at end of slide show!

14. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Computer Systems and their Importance Memory Management The OS manages the RAM. When you load an application, the OS will copy the application to the RAM. In addition, the OS will ensure that each program that loads has its own space on the RAM. This stops other programs reading and writing to the memory area for another application. It is also responsible for managing virtual memory. Learning Objectives: (a)Explain the need for the following functions of an operating system: user interface, memory management, peripheral management, multi-tasking and security. Operating System Applications

15. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Computer Systems and their Importance Peripheral Management Peripherals are devices that are attached to a computer such as a printer or speakers. The operating system controls these devices and gives programs access to them. When you print a document, the program doesn’t know how to talk to the printer, it doesn’t even know if one is installed. Instead it passes this data to the operating system which in turn passes it to the printer. The same happens when you save a file. The program passes this information to the operating system and the operating system is what saves files onto the hard disk. Learning Objectives: (a)Explain the need for the following functions of an operating system: user interface, memory management, peripheral management, multi-tasking and security. Operating System Applications

16. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Computer Systems and their Importance The User Interface The word interface means ‘coming together’. In computers, an interface enables a user to interact with a computer. Operating Systems provide users with an interface so that they can interact with the computer. Operating systems will usually offer one of three major types of interface: -Graphical User Interface (GUI) -Menu Driven Interface -Command Line Interface Learning Objectives: (a)Explain the need for the following functions of an operating system: user interface, memory management, peripheral management, multi-tasking and security. Operating System User Software

17. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Computer Systems and their Importance Graphical User Interfaces Uses windows, icons, menus and pointers (WIMP) to control the computer. Only been around since the mid 80s. Windows and Apple Mac OSx are examples of this kind of interface. Menu Driven Interface Uses menus to control the computer. These were very popular on early mobile phones and are seen in all high streets on cash machines and also on many MP3 players. Only offer limited functions (ie. if it is not on the menu then you can’t do it!) Command Line Interface Used to be the only way to interact with a computer (pre-80s) and is still used today by ‘Linux users’ and other professionals with technical knowledge. With this kind of interface ‘written commands’ control computers.

18. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Computer Systems and their Importance Multi-Tasking As we know, a CPU’s core works one process at a time. An operating system enables multi-tasking by managing the CPU’s processes so that several programs can run at once. On old computers, a CPU would focus on the processes of one program. On a multi-tasking operating system, many programs can run at the same time. The operating system enables this to happen by either allowing processes to take it in turn, or getting the shortest job done first. Because CPU’s are so quick now-a-days, it appears to be simultaneous and allows many programs to be used at once. Learning Objectives: (a)Explain the need for the following functions of an operating system: user interface, memory management, peripheral management, multi-tasking and security. Operating System User App

19. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Computer Systems and their Importance Security Often computers will be used by several users. Operating systems manage these users and ensure that a user’s data is only seen by them and not by others. In this way an OS provides security to users. They give users ‘usernames’ and ‘passwords’ so that data is kept secure. They also give different users different permissions. This means that one user may be given permission to install new programs whereas others cannot. In this way, an operating system can ensure that a computer system is not open to abuse from any user. Learning Objectives: (a)Explain the need for the following functions of an operating system: user interface, memory management, peripheral management, multi-tasking and security.

20. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 1 What does the ‘Operating System’ do with peripheral devices?

21. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 2 What does the word ‘Interface’ mean?

22. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 3 What is a GUI?

23. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 4 If you are writing a document and you press print, does the program know how to communicate with the printer?...why? Remember: Answer in full sentences

24. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 5 What do ‘Operating Systems’ provide to enable users to interact with a computer?

25. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 6 When programs are opened, they are copied onto the RAM How does the ‘Operating System’ stop these opened programs reading and writing to the memory areas of other programs?

26. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 7 If you are writing a document and you press print, does the program know how to communicate with the printer? Remember: Answer in full sentences

27. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 8 When you save a file in a program, what role does the ‘Operating System’ play?

28. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 9 What are the three major interfaces that ‘Operating Systems’ provide?

29. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 10 How can an ‘Operating System’ prevent a computer system from being open to abuse/sabotage from its users?

30. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 11 If a CPU core can only deal with one process at a time, why do modern computers appear to have several programs working all at the same time (simultaneously)?

31. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 12 How does a ‘graphical user interface’ differ from a ‘command line interface’?

32. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 13 What is Multi-Tasking when it comes to a computer system?

33. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 14 How does a ‘menu driven interface’ differ from a ‘GUI’?

34. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 15 What is a peripheral device?

35. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 16 How does an ‘Operating System’ enable several programs to run at the same time when a CPU core can only actually deal with one process at a time? There are two methods – explain each.

36. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 17 Operating Systems can allow several users to use the same PC. How is this done?

37. GCSE Computing: A451 Computer Systems & Programming www.computerscienceuk.com Question 18 What is the most common type of interface that PC ‘Operating Systems’ offer?