Operating System (OS)

OS :-
It is system software which works as an interface between user and hardware.
Types of OS :-
(1) Single user OS :- Allows one user at a time.
Like PC.e.g. MS DOS.
(2) Multi user OS :- Allow multiple users at a time.
Like Network.e.g. Unix,Linux.
(3) Multitasking OS :- Work on more than one processor at a time and allow users to switch between running applications.e.g.Linux, Unix.
(4) Real Time OS :- Processing done within a time constraint.
Like Flight reservations,Military applications.e.g.HP-RT.
(5) Embedded OS :- It is self contained in the device & resident in ROM.
Like Microwave,washing machines.e.g.Win.CE.
(6) Batch processing OS :- No.of jobs are put together & executed as a group.e.g.Unix.
(7) Distributed OS :- Data can be stored & processed on multiple locations.
Like IBM RS/6000 e.g.Unix.
(8) Mobile OS :- Operates on smart phones,tablets & digital mobile phones.Mobile OS classified as :
*Android:- Introduced by Google in 2007.Based on Linux.e.g.kitkat.lollipop.
*Symbian:- Developed by Symbian Ltd.
*IOS:- Developed by Apple inc.
*Blackberry:- Developed by blackberry company.
(9) Multiprogramming OS :- More than one program reside in main memory, when one job fails it switches to another program & allow that to run.
Like Excel,chrome.e.g.Win., Unix.
(10) Time sharing OS :- Provides scheduling to each process to be run on.e.g.mac OS 
(11) Server site OS :- Also called Network Operating System (NOS). It is complete set of files,tasks and job management.e.g. Linux,Unix,Solaris.

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