Operating System is system software. This is software acts as an interface between the user and the computer. It also controls and coordinates different operations of computer. These operating systems are categorized of basis of users and their tasks.
a) Single user, Single Task: As the name implies, this operating system is designed to manage the computer so that one user can effectively do one thing at a time. The Palm OS for Palm handheld computers is a good example of a modern single-user, single-task operating system. When you are using MS-DOS it is a single user single task operating system.
b) Single user, Multi-tasking: This is the type of operating system most people use on their desktop and laptop computers today. Microsoft’s Windows and Apple’s MacOS platforms are both examples of operating systems that will let a single user have several programs in operation at the same time. For example, it’s entirely possible for a Windows user to write a letter and at the same time the printing of another letter can be done or at the same Internet browsing can be done.
So in Single user operating systems there is one keyboard and one monitor that you interact with.
Consider a typical home computer. There is a single keyboard and mouse that accept input commands, and a single monitor to display information output. There may also be a printer for the printing of documents and images.
In essence, a single-user operating system provides access to the computer system by a single user at a time. If another user needs access to the computer system, they must wait till the current user finishes what they are doing and leaves.
A multi-user operating system allows many different users to take advantage of the computer’s resources simultaneously. The operating system must make sure that the requirements of the various users are balanced, and that each of the programs they are using has sufficient and separate resources so that a problem with one user doesn’t affect the entire community of users. Unix, VMS and mainframe operating systems are examples of multi-user operating systems.
A multi-user operating system lets more than one user access the computer
system at one time. Access to the computer system is normally provided via
a network, so that users access the computer remotely using a terminal or
These terminals nowadays are generally personal computers and use a network to send and receive information to the multi-user computer system. Examples of multi-user operating systems are UNIX, Linux and mainframes such as the IBM AS400.
The multi user operating systems must manage and run all user requests, ensuring they do not interfere with each other. Devices which can only be used by one user at a time, like printers and disks must be shared amongst all those requesting them so that all the output documents are not jumbled up. If each user tried to send their document to the printer at the same time, the end result would be garbage. Instead, documents sent are placed in a queue, and each document is printed in its entirety before the next document to be printed is retrieved from the queue. It is similar to a situation where in you are waiting for your turn in a ticket counter to get a ticket. The ticket issuer issues the ticket when your turn comes. Here also all the printing jobs wait in a queue and jobs are printed one after the other. Some priority can also be set to some jobs so that they can be taken up early according to some priority.
Batch Processing Systems:
In these kinds of systems the user feeds his job into the computer and waits for the completion of his job. New job can not be started until the old job is not completed. Thus the jobs required to be processed are kept in ready state and whenever one job is completed the next job is automatically taken and executed.
Batch processing has these benefits:
It allows sharing of computer resources among many users,
It shifts the time of job processing to when the computing resources are less busy,
It avoids idling the computing resources with minute-by-minute human interaction and supervision,
By keeping high overall rate of utilization, it better amortizes the cost of a computer especially an expensive one.