Is a software that acts as an interface between the user, application software and the computer hardware
EXAPMLE OF OPERATING SYSTEM
- Microsoft Disk operating system ( Ms DOS)
- Windows ( 98, 2000, XP, vista)
- Linux
- Unix
- Shell – it is the outer part of an operating system and it is responsible of interacting with the operating system
- 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
- Job scheduling
- Interrupt handling
- It is a break from the normal sequential processing of instructions in a program
- 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.
- Memory Management
- It is where the operating system constantly assigns main memory storage partitions to data an instructions
- 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.
- Input/output handling
NOTE
What is interrupt request?
- Is a unique number that is given to a resource for identification purposes
- 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 operatind 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.
- Is where a particular task holds a resourcs and refuses to release it for othe tasks to use.
They are classified into three ways/types:-
- According to the number of tasks handled concurrently
- Single task – one task is operated at a any given time
- Multi-Task – More than one task is processed apparently simultaneously
- According to the number of users
- Single user – Single (One) user operates a computer at any given time
- Multi user – More than one user can operate the computer at the same time
- Human computer interface / G U I
- Interaction between the computer and the user.
- Command line – The user types the commands at the command prompt to activate them by pressing the enter key
- Fast in operation by experienced users
- flexible
- Use Less memory
- Don’t require expensive hardware
- 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
- Menu driven – The user is provided with a list of menu to choose from
- More user friendly than command line
- More easier to learn and understand
- Eliminates the problem of forgetting the syntax of command since commands are provided for you
Disadvantages
- Slow to operate
- Not flexible
- Graphical User Interface(GUI) – The user interacts with the computer using icons and menus and select them using pointer
- It is easy to learn and operate
- They make it easy to exchange information between application
- Reduce the user training time and cost due to their inform mode of operation
- It is more user friendly
- Supports multi user and multi task
Disadvantages
- Cost of GUI supporting hardware is higher
- Many objects on the GUI confuse new computer users
- - Require faster processors that are more expensive
WINDOW as used in operating system
Is a rectangular object created on a screen by operating system to contain input or output data for a particular program
PROPERTIES OF A WINDOW
- Title bar
- Display/ working area
- Horizontal and vertical scrolls bars
- Menu bars
- Status bar
- Tool bar
- Pop up menu
- Pop down menu
- Sub menu( Cascading/ Side kick menu)
COMPUTER FILES
Are classifies into types :-
- System Files
- Application Files
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