Types of operating system

1. A single-program system: - The system which only allow one user at a time to operate the machine in an interactive conversational mode but normally allow one user to be in main storage and processed at a time i.e., there is now- multiprogramming of users programs. These are the types of systems you usually find on Personal computers (PCs) (microcomputer based system). There are many such operating systems that fall into this category such as MSDOS produced by Microsoft.

2. Simple batch system: -The system which provide multiprogramming of batch programs hut have few facilities for interaction or multi-access.

3. Multi-access and Time-sharing systems:- The system which allow more than one user to operate machine sharing the processor time between users. The majority of operating system fall into this category, but there is a wide range of complexity in such system, there are number of operating system available in the larger microcomputers and  many minicomputers produced by  many different manufacturers including HP. SUN. SEQUENT. UNISYS. DEC and IBM. One such very common operating system is Unix, which was developed by {Bell Laboratory in the USA. On mainframes, operating systems are normally specific to the particular machine and manufacturer.

4. Real-time systems :-   The system which response very fast in time. The three types are:  

 

a) Multi-access a n d  t i m e - s h a r i n g:-  

Very complex where each user has largely independent choice of system facilities, eg. Each using a different language.

b) Commercial real time system:- In which one job is used essentially and the multi-access is used. E.g., Transaction in bank. where bank has to update immediately and the result has to display immediately. Commercial airliners use real-time operating system in their on-board computers, and some airlines have a continuously update display into passenger areas for the interest of the passengers.
The on-board computer constantly updates its estimate of arrival time, etc based on the current readings for wind velocity, direction an so on. Components of an Operating System

Time to destination:                            6:35
Estimated arrival time:                        12:10
Local lime at destination:                    5:35
Local lime at present position:            12:35

 

c) Process control system:- Real-time process control systems vary greatly in size. It is used in microprocessor-based instruments and monitoring device, e.g.. the control system in a service station petrol pump.

By now it should he clear that there are many types of systems, with different levels of complexity. Each of them may have different components, and there is no such a thing as a "standard composition" of any OS. What we shall see now is just a few of these components, namely, the more important ones from the user perspective. Basically the OS teaches the computer how to behave itself, how to handle peripheral devices and how to communicate with users.