1. OS Basics

3. 1 1 Key Concepts 2 2 A Bit of History 3 3 Activity - File System 4 4 Outline

4. OS Basics 1 1 Key Concepts 2 2 A Bit of History 3 3 Activity - File System 4 4 Outline

5. OS Basics 1 1 We said you can view a computer as a machine made of layers The OS sits in a special place in these layers It’s right between all the hardware and the apps we use for work & play

6. Operating System So a good OS makes everything look simple to the user who doesn’t worry what’s happening behind the scenes OS Basics 1 1 The OS sits between all the hardware & applications, managing the resources for the whole system.

7. OS Basics 1 1

8. 1 1 Software means all the programs that contain the instructions to tell the computer what to do. There are two main types of software: systems software and applications, which we’ll cover later. We’re now focusing on the operating system because it’s the prime example of systems software. A The Bigger Picture

9. OS Basics 1 1 The operating system controls the operation of the computer. It manages all the hardware and software or programs. And it provides a link between user and computer. Basically, a computer simply wouldn’t work without the operating system ! B What Is An OS ?

10. OS Basics 1 1 C Two Types of OS Controls the server behind the scenes in a network. Server OS Client OS Controls a computer for one user.

11. OS Basics 1 1 D How The OS Takes Over BIOS Storage OS Memory CPU 1 1 Computer boots using the BIOS ROM 2 2 The OS is loaded from storage into RAM 3 3 The CPU starts the fetch-execute cycle 1 1 2 2 3 3

12. OS Basics 1 1 The OS handles several key functions in a computer, such as: 1) User interface 2) Multi-Tasking 3) Memory Management 4) File Management 5) Peripheral Management 6) Security 7) Utilities More follows on the ‘Extra’ pages. E Functions of an OS

13. OS Basics 1 1 The OS uses programs called utilities to handle housekeeping tasks, such as: Anti-virus: Utility to protect from malicious programs called viruses System Clean-up: Deletes old system files to clear storage space Disk De-frag: Re-arranges files on a hard drive to improve access times Software Updates: Automates downloads of software updates E Functions of an OS

14. OS Basics 1 1

15. 1 1 i User Interface A Graphical User Interface (GUI) uses windows, icons, menus & the pointer ( WIMP ). Graphical Command Line A Command Line Interface (CLI) uses a prompt where users type commands, such as with Linux.

16. OS Basics 1 1 ii Multi-Tasking BIOS Storage Software Memory CPU The OS makes it possible to run several programs at once.

17. OS Basics 1 1 iii Memory Management BIOS Storage Software Memory CPU The OS also divides up the RAM to share it between different applications.

18. OS Basics 1 1 iv File Management Software The OS organises all the files you install or save on storage, such as the hard drive Storage

19. The OS manages connections with i/o peripherals using special programs called device drivers. Device Drivers v Peripheral Management

20. iv File Management The OS provides security by handling logon accounts and passwords, as well as access rights.

21. OS Basics 1 1

22. Going forwards, you will need to keep this general background in mind to understand what an OS is doing overall OS Basics 1 1 But we’ll actually focus on only a few key concepts for an OS…

23. OS Recap 1 1 Key Concepts 2 2 A Bit of History 3 3 Activity - File System 4 4 Outline

24. You’ll now be making some quick notes in this booklet… Key Concepts 2 2

25. One key concept is the User interface – and remember there are two types… Graphical User Interface This is the WIMP interface that we’re all used to Command Line Interface This is the text-based interface that’ll also soon become familiar! Key Concepts 2 2

26. Another key concept is the File System, which is how the OS manages what needs storing… Folders Is how the OS organises what’s stored in a computer & other devices Files Is the actual data in various file types, such as documents and media Key Concepts 2 2

27. And a final key concept is User Management, which is controlling who can access resources System Administrators Means the ‘admins’ who have the most rights & privileges to run things Ordinary ‘Users’ Means normal people who have less ‘rights’ when using a computer Key Concepts 2 2

28. So our first goal for these prep lessons is to use the Windows GUI to do admin on files & users Key Concepts 2 2 And our final goal is to introduce you to using Linux and its command line to do admin tasks That will be more tricky – but also more fun! Our second goal is to explore the command line in Windows for doing those admin tasks

29. OS Recap 1 1 Today’s Lesson Key Concepts 2 2 A Bit of History 3 3 Activity - File System 4 4

30. A Bit Of History 3 3 We’ll now pause for a quick history lesson! That’s because it will help us focus on key concepts such as the user interface and file systems and why they work the way they do…

31. 19501960 197019902000 1940 2010 1980 Unix 71 MS-DOS 81 Mac OS 84 Win 1.0 85 Android 1 2012 Linux 91 Bill Gates Thompson & Ritchie Steve Jobs Linus Torvalds

32. A Bit Of History 3 3 So each OS has influenced the others Unix is like an ancestor to lots of operating systems, such as Linux And Windows started life as MS-DOS & that remained its core for years Now Linux is used as the core of Android, the mobile OS from Google So it’s worth noting that OS are also built in layers from a core…

33. OS A Bit of History 3 3 Applications Programs that we use for work & play Libraries & Tools Kernel Hardware Libraries & Tools Set of programs that extend the kernel with features such as the user interface. Kernel Is the core of the operating system that interfaces with the hardware

34. A Bit of History 3 3 Applications Windows Libraries & Tools MS-DOS Hardware MS-DOS Was the original core of Windows and is the forerunner of today’s Command Line

35. A Bit Of History 3 3 So the origins of the command line interface lie with the original operating systems, such as Unix and MS-DOS That means that all file handling, for example, was done using text So no nice icons for folders and files! That has had a big influence on File Systems for all operating systems We’ll explore that now with an activity

36. A Bit of History 1 1 Today’s Lesson OS Recap 2 2 Key Concepts 3 3 Activity - File System 4 4

37. 4 4 The File System means the methods used by an OS to name & store files so they can be opened quickly and easily The File System lets to access files on storage devices, such as the hard drive It also allow us to access external storage devices, such as USB sticks And is even includes network ‘drives’, such as ‘Student Resources’

38. Activity - File System 4 4 Ordinary computer users understand this by saying they put files into folders But we need to start learning how computer scientists look at file systems And that includes some new terms for familiar words…

39. Activity - File System 4 4 For a start, ever since the days of Unix, computer scientists say that files are stored in directories, not folders And directories are organised in a hierarchical structure called a tree Here is an example of the start of what’s called a tree directory structure…

40. My Documents Yes – this is a geeky version of a tree! Computer scientists actually love trees Not to hug…but to show data structures… Hard Drive (C:) HomeWork

41. My Documents Hard Drive (C:) HomeWork Branch Root Leaf

42. Branch Root Leaf

43. These are classic terms in computer science There are lots of algorithms for using trees And many ways to structure data in ‘trees’

44. My Documents Hard Drive (C:) HomeWork So a ‘tree’ is the classic way to handle files Behind the scenes, the OS uses a tree structure Not with cute ‘GUI’ icons but using paths…

45. Hard Drive (C:) It all starts with the ‘root’ directory Root is always given a letter as a label ‘C’ is traditional for a hard drive on Windows C:\ Root

46. My Documents Hard Drive (C:) Now we move to the next directory And add the next part of the path… It’s starting to look a bit like a web address… C:\ My Documents

47. Hard Drive (C:) Home C:\ My Documents Here’s the next directory & updated path… \Home

48. My Documents Hard Drive (C:) HomeWork My Documents And the final directory, with another slash… \Work C:\

49. Activity - File System 4 4 So here’s a completed file path… My Documents \Work C:\ Root Is the hard drive for C: Directory Is a folder Back slash Opposite to websites!

50. Activity - File System 4 4 Let’s now expand that idea to a typical set of folders (directories) and files that someone might store. Imagine these are the files for someone called Sally She’s not like a typical teen Her stuff is organised…! So we can practice with paths

51. HomeWorkClub Members Report.doc Game.swf My Documents Song.mp3 Video1.mp4Page.html Budget.xls Shopping.txt Poster.pdf Database.mdb TrainingPhotos Beach.jpg Graphic.gif Meeting.ppt