OPERATING SYSTEMS

                                 OPERATING SYSTEMS

• Is a software that acts as an interface between the user, application software and the computer hardware

EXAPMLE OF OPERATING SYSTEM

1. Microsoft Disk operating system ( Ms DOS)
2. Windows ( 98, 2000, XP, vista)
3. Linux
4. Unix

PARTS OF OPERATING SYSTEM

1. Shell – it is the outer part of an operating system and it is responsible of interacting with the operating system
2. Kernel – Responsible for managing and controlling computer resources such as the processor, main memory, storage devices, input devices, output devices and communication devices

RESOURCE UNER THE OPERATING SYSTEM CONTROL

• The processor
• Main memory
• Input/Output Device
• Secondary storage devices
• Communication devices and ports

FUNCTIONS OF OPERATING SYSTEM

1. Job scheduling

– it is the process of the operating system to keep list of jobs currently being run by the computer and clocking them in and out of the processor.

1. Interrupt handling

• It is a break from the normal sequential processing of instructions in a program

1. Resource control and allocation

• It is situation where the processor gives a computer resources a unique number called interrupt number so that it can be able to recognize and prioritize it.

1. Memory Management

• It is where the operating system constantly assigns main memory storage partitions to data an instructions

1. Error handling

• It is a situation whereby an operating system alerts the user of errors that arises in ease of illegal operations, hardware or software failure.

1. Input/output handling

NOTE

What is interrupt request?

• Is a unique number that is given to a resource for identification purposes

What is the importance of interrupt computer

• To enable urgent tasks/ processes to b given the first priority during program execution

What is virtual memory

• Part of the hard disk that acts as maim memory
• Operating system organizes the main memory in blocks called page frames. The processes are divided into partitions that can fit in a page. The operating system swaps these pages between the main memory and the hard disk. The part of the hard disk where these pages are held in the virtual memory.

What is a deadlock

• Is where a particular task holds a resources and refuses to release it for other tasks to use.

CLASSIFICATION OF OPERATING SYSTEM

They are classified into three ways/types:-

1. According to the number of tasks handled concurrently
2. Single task – one task is operated at a any given time
3. Multi-Task – More than one task is processed apparently simultaneously

1. According to the number of users
2. Single user – Single (One) user operates a computer at any given time
3. Multi user – More than one user can operate the computer at the same time

1. Human computer interface / G U I

• Interaction between the computer and the user.

1. Command line – The user types the commands at the command prompt to activate them by pressing the enter key

Advantages

• Fast in operation by experienced users
• flexible
• Use Less memory
• Don’t require expensive hardware

Disadvantages

- Hard to learn and understand

- Not user friendly

- If you mistype or forgot the syntax of writing the command, you cannot operate it

- Difficult to learn

- Difficult to move information from one application to another

- Difficult to design and produce printed reports

- Do not support multi-users and multi-task