This Blog provide simple notes in simple language of computer science and engineering.

Monday, 11 February 2019

Define operating system

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Definition-1:
An operating system is a program that manages the computer hardware. It also  provides a basis for application programs and acts as an intermediary between the  computer user and the computer hardware. The purpose of an operating system is to  provide an environment in which a user can execute programs in a convenient and  efficient manner.

Definition-2:
A computer system has many resources that may be required to solve a problem. The  resources can be CPU time, main memory space, file-storage space, I/O devices, and so  on. The operating system acts as the manager of these resources. Operating System is  also called as a control program that manages the execution of user programs to prevent  errors and improper use of the computer.

Definition-3:
An operating system is a program that controls the execution of application programs  and acts as an interface between the user of the computer and the computer hardware.  An OS has three major objectives:  Execute user programs and make solving user problems easier   Make the computer system convenient to use   Use the computer hardware in an efficient manner

 Definition-4:
Operating System is the one program running at all times on the computer - usually  called the kernel. (Along with the kernel, there are two other types of programs: System Programs which are associated with the operating system but are not part of the  kernel, and application programs which include all programs not associated with the  operation of the system.) Definition-5: The operating system is the most fundamental piece of software and it runs in kernel  mode (also called supervisor mode). In this mode it has complete access to all the  hardware and can execute any instruction the machine is capable of executing. The rest  of the software runs in user mode, in which only a subset of the machine instructions is  available. In particular, those instructions that affect control of the machine or do I/O  (Input/output) are forbidden to user mode programs.

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