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

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

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

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

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

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

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

Photoshop CC 2014 system requirements

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

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

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

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

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

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

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

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

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

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?

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

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)

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

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

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

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

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 Email filter & web filters

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?