1. Systems Software Operating Systems

2. What is software? Software is the term that we use for all the programs and data that we use with a computer system. Two types of software Program The instructions that the computer follows (e.g. a word processor or a game). Data What the programs process (e.g. a word processing document or a saved game)

3. More on software There are two types of program software. Applications software Programs designed to carry out a manual task (Word Processors, Databases, Graphics etc.) Systems Software Programs used to organise the computer, handle its devices, manage memory etc. The Operating System is Systems Software

4. Operating Systems The operating system (OS) is the most important program used by the computer. The OS organises many things within the computer.

5. Operating Systems (OS) The OS is stored on hard disc and loaded into RAM when the computer starts up. Some computers store their OS in ROM so that it cannot be erased by accident. The operating system controls and monitors the operation of the computer system.

6. Examples of OS Windows Linux Mac OS Unix for large file servers and networks

7. Standard Functions of the OS User interface (HCI) The OS provides the means of the user communicating (interacting) with the computer system Features such as windows, icons, menus, commands, etc. are all provided by the operating system Open word processor 1011 0110 OS

8. Standard Functions of the OS Controls input/output The access to all devices attached to the computer is controlled by the OS. For example, the OS can stop two programs trying to use the same device at the same time.

9. Standard Functions of the OS Manages memory Controls where programs and data are placed in the main memory. Error Reporting The operating system lets the user know if any mistakes have occurred E.g. No paper in printer

10. Standard Functions of the OS File Management It controls access to all types of backing storage devices It will prevent two programs trying to access the same files at the same time. Data stored in backing storage in areas called Directories (Windows call them folders)