Unit A451: Computer systems and programming. Section 3: Software 1 Intro to software

Transcription

1 Unit A451: Computer systems and programming Section 3: Software 1 Intro to software

2 Section Objectives Candidates should be able to: (a) Understand the basic functions of an operating system (b) Explain the need for the following functions of an operating system: memory management, peripheral management, multitasking and security

3 Operating Systems Operating Systems are the core software that allow users to interact with and use computers. They are essential in order to make the hardware inside our computers function correctly.

4 Functions of an Operating System User Interfaces The operating system provides a way for us to interact with the hardware and software. This is known as an _

5 Functions of an Operating System User Interfaces The operating system provides a way for us to interact with the hardware and software. This is known as an Interface

6 Functions of an Operating System User Interfaces Recap MS-DOS was an early operating system that enabled a user to type instructions for the computer to carry out. What is this type of interface known as?

7 Operating Systems This is known as a Command Line Interface

8 Functions of an Operating System User Interfaces Recap What were the other 2 types of interface known as?

9 Menu Driven Interface

10 Graphic User Interface

11 Functions of an Operating System An operating system ensures our computer runs as expected. To do this it performs a number of tasks and has a number of vital functions in computer systems.

12 Functions of an Operating System These roles include Providing an interface Memory Management Peripheral Management Multi-Tasking Security

13 Memory Management You computer only has a limited amount of Memory (for example 4gb) The operating system has something built in known as a memory manager. When you open, and are working on an application it is stored in the RAM (memory)

14 Memory Management The memory manager is responsible for removing and adding programs and removing them when they are no longer needed. Without this the RAM would become overloaded and the computer would no longer be able to operate.

15 Peripheral Management Peripherals are any computer hardware components that are not part of the CPU. This includes input devices, output devices and storage. When a new peripheral is added, a software driver is needed to allow the OS to understand and install the device. The OS then allows the PC and all peripherals to communicate with each other.

16 Multi-Tasking A computers CPU can only carry out one instruction at a time, but has many different programs running at once. This is because the OS cleverly (and quickly!) allocates data to and from the CPU, prioritising the programmes need data processing before others. Because all of this happens in milliseconds, it gives the impression of all the programs working at the same time. Multi-Tasking.

17 Security The OS provides different levels of user access and password protection to keep unauthorised users out of the computer system. It decides on file permissions. This determines who can see certain folders / files and who can alter or delete them. It may also provide backup and recovery routines for recovering the system in the event of a system failure.