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

2. Lesson Aims  By the end of this lesson:  All pupils will be able to:  Describe what an operating system is  Describe what an application program is  Describe the functions of an operating system

3. Types of software  There are two main types of software:  Applications  These are pieces of software that perform a particular task such as word processing or desktop publishing  Systems Software (Operating Systems)  These types of software control the running of hardware and the running of other software Nat 4/5

4. Applications Software  Application software are programs that are designed to do a particular task.  For example the Word Processor your revision notes were written in is an application program. Nat 4/5 Even games are application programs.

5. Operating Systems  An operating system is a piece of software that controls the operation of the systems hardware and the running of other software.  Two of the more popular operating systems used at present are  Microsoft® Windows  Apple® OSX. Nat 4/5

6. Why is it important?  You are writing an app for a smartphone  Which operating system do you write it for?  IOS® Android ® Windows ® ?  Why do you need to bear this in mind?  If I buy Office 2010 for windows – can I install it on a Mac? Nat 4/5

7. Operating Systems: Functions  All operating systems have certain common functions : Nat 4/5 Provision of an Interface This is the means of interacting with the user. Most modern operating systems provide a GUI (Graphical User Interface) Input Output Controls the sending and receiving of data to and from peripherals Memory Management Controls the systems RAM, controlling which locations in RAM programs are loaded into File Management Controls where and how files are saved onto backing storage. Error Reporting Providing useful feedback to users when errors do occur.

8.  An emulator is a utlility program which allows a computer to run a different operating system.  This gets round the problem of not being able to run software because it has been written for a different operating system.  An example is “Parallels Desktop” which allows an Apple computer to run Windows software Emulators

9. Summary  The Operating System (OS) of a computer is a program which manages the hardware and the running of other software on a computer system.  The standard functions of an OS are:  Provision of a human/computer interface  Input/Output  File Management (backing Storage)  Memory management (RAM)  Error Reporting Nat 4/5

10. Summary (2)  An application program is a piece of software that performs a particular task such as games, word processers.  An emulator is a utlility program which allows a computer to run a different operating system. Nat 4/5