What is Operating System? Operating System is a group of a program that controls all the operation of a computer system and its components. It is an integrated set Of specialized programs that are used to manage the resources and overall operation of a computer, A computer can do nothing without an operating system. It must be installed on every computer. A user interacts with the computer through Operating System. When a computer is turned on, the operating system runs and checks that all parts of the computer are functioning properly. An operating system manages all operation on a computer after loading, some popular operating system is IBM PC-DOS, MS-DOS, UNIX, XENIX, LINUX, WINDOWS-98, WINDOWS-2000, OS/2, and WINDOWS-XP.
TYPES OF OPERATING SYSTEM
An operating system is classified according to the following criteria ‘s.
1. Single User Operating Systems
2-Multi-User Operating Systems
SINGLE USER OPERATING SYSTEM
Single User Operating system allows only one user to use the system. For Micro-computer single-user operating system offer the following function.
1- Initialization of System; in which the OS must have initial loader program to initialize the system properly.
2- File Management; An operating system contains file management programs that control the creation, deletion, and access to files of data and program.
3-Memory management. In this type of operating system, this memory management is simple, as only one application is executed at one time. If there is another application to be run the previous is removing from the memory.
4- Input-Output management: I/O management in this type of O.S is simpler as compared to Other because the one I/O device is made active at a time.
MULTI-USER OPERATING SYSTEM
Multi-User Operating system allows more than one user at a time to use the system.
The function provides by OS are:
1- Initialization. Initialization is more complex than single-user operating system because it is possible that more than one computer be initialized by a server.
2- File Management. File Management is more complex in this case because a file maybe accesses or shared by more than one user. If a user is using currently a file and another user also trying to access this file than it is the duty of operating system to lock the file for other uses and also see Security (permissions) on file also share a file to available it Network.
3- Memory management; it available memory of server is divided among different user the rest of memory management is the same as the single OS. It also uses a technique called paging to allow your computer to run more programs than its physical memory by storing memory pages not currently in use on a mass storage device called virtual memory.
4- Input-Output Management. It is also complex because of more than one devices managed by OS.
5-Resource Management; Resources (Printer, CD Drive, Floppy Drive etc are available to all user on a network) these devices can be share to access from other computers.
6- process Management; In a multi-user operating system, more than one application is executed at a time this capability is called multitasking.
7- processor Management. In a multi-user operating system more than one user connected to the system. Hence the processing speed must be fast to manage all user requests. For this reason, a system must have more the one processor. a multiuser system has the capability to manage all these processors.
8- Communication Management; In a multi-user operating system, one computer is connected with more than one systems. Hence it has the capability to create new user, groups and assign Passwords and permissions.
It usually consists of a “dump” type terminal connected by data lines to a centralized Micro-Computer based system that controls all operations.