Operating System

 

It is a program with the following features:

·         An the operating system is a program that acts as an interface between the software and computer hardware.

·         It is an integrated set of specialized programs that are used to manage overall resources and operations of the computer.

·         It is a specialized software that controls and monitors the execution of all other programs that   reside in the computer, including application programs and other system software.

·         When you turn on a computer, it goes through several steps to prepare itself for use. The first step is called the power-on self-test (POST). The computer identifies the devices attached to it, identifies the amount of memory available, and does a quick check to see whether the memory is functioning properly. This routine is initiated by a part of the system software located in read-only memory (ROM), a chip that contains brief, permanent instructions for starting the computer.

 

Objectives of the Operating System

·         To make a computer system convenient to use in an efficient manner

·         To hide the details of the hardware resources from the users

·         To provide users a convenient interface to use the computer system

·         To act as an intermediary between the hardware and its users and making it easier for the users to access and use other resources

·         To manage the resources of a computer system

·         To keep track of who is using which resource, granting resource requests, according to a resource using and mediating conflicting requests from different programs and users

·         To provide efficient and fair sharing of resources among users and programs

·         An the operating system is a program that acts as an interface between the software and computer hardware.

·         It is an integrated set of specialized programs that are used to manage overall resources and operations of the computer.

·         It is a specialized software that controls and monitors the execution of all other programs that   reside in the computer, including application programs and other system software.

·         When you turn on a computer, it goes through several steps to prepare itself for use. The first step is called the power-on self-test (POST). The computer identifies the devices attached to it, identifies the amount of memory available, and does a quick check to see whether the memory is functioning properly. This routine is initiated by a part of the system software located in read-only memory (ROM), a chip that contains brief, permanent instructions for starting the computer.

 

Objectives of the Operating System

·         To make a computer system convenient to use in an efficient manner

·         To hide the details of the hardware resources from the users

·         To provide users a convenient interface to use the computer system

·         To act as an intermediary between the hardware and its users and making it easier for the users to access and use other resources

·         To manage the resources of a computer system

·         To keep track of who is using which resource, granting resource requests, according to a resource using and mediating conflicting requests from different programs and users

·         To provide efficient and fair sharing of resources among users and programs

        Operating System first load in a computer before it can be used for any useful work.

 

 Characteristics of Operating System

        Memory Management -- keeps tracks of primary memory i.e. what part of it is in use by whom, what part is not in use etc. and allocates the memory when a process or program requests it.

·         Processor Management -- allocates the processor (CPU) to a process and deallocates processor when it is no longer required.

·         Device Management -- keeps track of all devices.  This is also called the I/O controller that decides which process gets the device, when, and for how much time.

·         File Management -- allocates and de-allocates the resources and decides who gets the resources.

·         Security -- prevents unauthorized access to programs and data by means of passwords and similar other techniques.

·         Job accounting -- keeps track of time and resources used by various jobs and/or users.

·         Control over system performance -- records delays between a request for a service and from the system.

·         Interaction with the operators -- The interaction may take place via the console of the computer in the form of instructions. Operating System acknowledges the same does the corresponding action and informs the operation by a display screen.

·        Error-detecting aids -- Production of dumps, traces, error messages and other debugging and error-detecting methods.

·         Coordination between other software and users -- Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems.