FUNCTIONS OF OPERATING SYSTEM

A Computer System is made up of Hardware, Operating System and user interface. Computer Software can be divided into System programs which manage the operation of the computer itself and the application programs, which solve problems for their users.

Operating System is the most fundamental of all the System programs. The Operating System controls the entire Computers’ resources and provides the base upon which the application programs can be written.

Operating System has been defined in different ways by different people. Some of the definitions are: An Operating System is program that makes the computing power available to users by controlling the hardware.

Another definition is that Operating System is a program that controls the execution of application programs. It masks the details of the hardware to application programs.

Operating System can be summarily defined as: a set of processes permanently or transitively resident within the Computer that makes the resources of the computer system available to the user in a consistent, reliable, friendly way. In essence it should be a Resource optimiser and operation

Operating System can be divided into the Kernel and the Operating System. The kernel is the essential centre of a computer operating system, the core that provides basic services for all other parts of the operating system. A synonym is nucleus. A kernel can be contrasted with a shell, the outermost part of an operating system that interacts with user commands. Kernel and shell are terms used more frequently in UNIX and some other operating systems than in IBM mainframe systems.

TYPES OF OPERATING SYSTEM

Single User

Single-user allows one single user to login at a time. There is no user account database which makes the level of security low and so users cannot protect their files from being viewed, copied or deleted. Examples of this type are DOS and Windows 98.

Multi-user

The Multi-user has a user database account which states the right that users have on certain resources. They are more secure than the single user since access is limited. Example of this is UNIX

Networked/Work alone/

Stand alone are usually not connected to a network and thus cannot access networked resources. They are usually more secured than and remote users cannot log into the computer. A network operating System uses a standard communication protocol for UNIX networks and over the internet( we have the TCP/IP). For Novell Netware internetwork Packet Exchange /Sequenced Packet Exchange (IPX/SPX). They are less secure than Standalone and should be protected (most times by creating user accounts. More examples are Windows NT 5.0, Windows 98,

MULTI-TASKING/SINGLE TASKING:

multitasking allows one or more programs to run, at time. Each process is given a prioritised amount of time on the processor. Single-user allows are programs to run at a time. It is usually faster than multi-tasking Systems +as some time is taken to in switching in multi-user. But multi-user is more efficient as they allow other tasks to run when a task is not performing any operation. Single-users are more robust, as multi-programs are require to communicate with each other which can cause synchronization problems (deadlock)

Multi Processor/Single Processor: Some Operating System allows for more than one processor to use on the system. This allows more than one task to be run, at a time, on different processors. Windows NT/2000 supports multi processors (up to 4).

Single Processor, Multitasking involves running each of the processor for a given time slice or a single processor where with multi processor, they can all run at the same.

FUNCTION OF OPERATING SYSTEM

Usually Operating system is there to manage all pieces of a complex system

Imagine what will happen if three programs running on a computer all try to print their output simultaneously on the same printer. The first few lines might be from program one and the next few lines might be from program two and so on with the result resulting in chaos. The operating system can bring order to potential chaos by buffering all the output destined for the printer on the disk.

The primary task of operating system is to keep track of who is using which resource, to grant resource request, to account for usage, and to meditate conflicting request from different programs and users.

When a computer has multiple users, the need for managing and protecting the memory, input/output devices and other resources are even more apparent. This need arises because it is usually necessary to share expensive resource such as tapes drives and phototypesetters.

Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.

For large systems, the operating system has even greater responsibilities and powers. It is like a traffic cop -- it makes sure that different program and users running at the same time do not interfere with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system.

The set of software products that jointly controls the system resource using these resources on a computer system is known as operating system. Examples are Unix, Windows.