What are the function of an Operating System? Differentiate between multiprogramming, multiprocessing. Which OS are single user and multiusers? Give example of each.

An Operating System has four major functions. They are:-

(a) Memory management

(b) Processor management

(c) I/O management

(d) Information management

MULTI-PROGRAMMING:- It is the process by which CPU executes programs that reside in memory on time sharing basis. In a multi programming environment, multiple programs are allowed to reside in memory at the same time. Processor executes one program for a short time and then next one is executed for short time and so on until all programs are executed for a short interval. Then it again take up the first one and execute for another short interval and then next one and so on. This process is repeated until programs are completely executed. If a program is completed it is removed from memory and next program that is ready is loaded into the memory.

  

MULTIPROCESSING:- In a multiprocessing system there will be more than one processor. Since there are more than one processor, more than one activity can be performed at the same time.

An example of single user operating system is DOS. An example of multi-user operating system is UNIX.