Skip to main content

Multi Programming Operating System

 Multi programming system

·         Multi programming operating system allows multiple users to execute multiple programs using a single CPU concurrently i.e. at the same time.

·         In multiprogramming several process are kept in the main memory and CPU execute all these processes concurrently. It means, the CPU immediately switches from one process to next that are ready to get executed

·         In such an operating system when one process start process start performing the instructions from several programs at the same time.

·         Rather, it means that there are number program available to CPU and that portion of one is executed, then segment of another and so on

 

 

 


                              memory layout in multi programming system

 

 

·         In case of multiprogramming the various jobs residing in the main memory, can be in one of the following three stages

1.       Running : CPU is being used by the program

2.       Blocked : performing I/O operation

3.       Ready : waiting for CPU to be assigned to it

·         The various example of multiprogramming operation system are windows NT,OS/2, UNIX.

·         A typical scenario of jobs in multiprogramming system . at a particular instance of time , program A is not utilizing CPU as it is busy writing output data on the disk.


       single user operating system  

2.      Multi user operating system 

3.       Batch processing operating system

4.      Multi programming operating system 

5.     Multi tasking operating system 

6.       Multiprocessing operating system

7.       Time sharing operating system

8.     Real time system  

programming

The various feature required by multi programming system are:

1.        large memory

·         For a multi programming to work satisfactorily, large main memory is required to accommodate a good number of user programs along with operator system.

 

2.       Memory protection

·         Computer designed for multi programming must provide some type memory protection mechanism to prevent a programing one memory partition from changing information or instruction of a program in another memory partition.

 

3.       job status preservation

·         in multiprogramming when one running job is blocked before I/O operation ,the CPU is taken away from that job is given to some another job later on when that job has finished its I/O operation, it need to be resumed with its execution.

 

4.       Proper job mix

·         A proper mix of I/O-bound and CPU-bound processes is required so that the operation of CPU and I/O devices are balanced.

·         If all the loaded jobs need I/O At the same time  , the CPU will be adle.

                                             

                                                           jobs in multi programming system

 Advantages and disadvantages of multi programming

Advantages of multi programming:

1.       Increased throughput. Throughput increased by utilising the idle-time of CPU for running other program that are already present in the main memory.

2.       Lowered response time. Response time is lowered by recognising the priority of job as it enters the system and by processing jobs on a priority basis.

3.       Ability to assign priorities to job.  Most multi programming systems have scheme for setting  priorities for rotating programs. They specify when the CPU will rotating programs. They specify when the CPU will rotate to anther program, and which program it will rotate to.

Disadvantages of multi programming

1.       Multi programming is implemented through an operating system, which is a program that requires space in primary storage since it must be executed by the CPU. The operating system overhead os greater with multi programming that with batch processing.

2.       Jobs may have different sizes, therefore memory management is needed to accommodate them in memory .

3.       Many jobs may be ready to run on the CPU, which means that CPU scheduling is required.

 

 

One of the requirement of multi programming is the given below:

1.       CPU scheduling

·         In a multi programming system ,often  there will be situations in wich two or more jons will be in the ready state, waiting for CPU to be allocated for execution.

·         In such a case, the operating system must bdecide to which process or jobs should CPU be allocated..

·         For this a CPU scheduler select the processes and uses different CPU scheduling algorithm.

Comments

Post a Comment

Popular posts from this blog

Functions of Operating System

  Functions of operating system   5.                     protection and security : ·                       another important functions of an operating system is to protect itself from the user process and to protect different users processes from one another in a syatem. ·                       In a multi programming environment, where several users process reside in main memory at the same time, the may interface with OS or with each other. ·                       Thus, protection mechanism controls the access of users, programs and processes used by various applications. ·                       A total approach to computer security involves both external and internal security.   6.                     Networking: ·           Networking is used for exchanging    information among different computer that are distributed across various location. ·           Distributed system consist of multiple processors and each processor has its own memory and clock ·           This results in compu
2 comments
Read more

OS its Resource Manager and its Function

  Operating system as resource manager:   ·           A computer system usually has many hardware and software resources such as processor , memory, disk printer, I/O devices etc. ·           The task of resources management becomes essential in multi-user operating system where different user compute for the same resource.   Operating system manages resources in two ways : 1.         Time multiplexing : it defines the sharing of resources on the basis of fixed time slices. For example, the operating system allocate the resources, such as CPUto program A for fixed time slice. 2.         Space timing:  it defines the concurrent sharing of resources among different programs.for example, sharing of hard disk and main memory is space multiplexing.     FUNCTION OF OPERATING SYSTEM     The primary function of an operating system is to provide an environment for excecution of users program . the various function of operating system are: 1.         process management 2.         main memory man
2 comments
Read more

Defination of OS(operating system) and its concepts

    What do you mean by operating system?     Definition :  An operating system is a program that act as an interface between the user of a computer and the                                      Computer hardware. Operating system is a first program that gets loaded into the memory through a process called booting. Concepts of operating system : ·                       The purpose of operating system is to provide an environment in which a user can execute program in a convenient and efficient manner. ·                       Operating system is an integrated set of program that manages the various hardware resources such as processor, memory, I/O Devices , communication devices and overall operation of a computer system. ·                       Operating systems also acts as a platform on which various applications programs such as word processor and excel are executed. ·                       The most common operating system are the window family of operating system (windows 98, window
3 comments
Read more

Multitasking System

  Multitasking system ·           Technically , multitasking is same as multi programming ·           In a multitasking operating system, s single user can execute multiple programs at the same time ·           We can also say, multitasking is the system capability to work on more than one job or process at the same time. ·           It means that whenever a job needs to perform I/O operation, the cpu can be used for execting some other job                                                        diagram of multi tasking     ·           There are two type of multitasking : 1.         Cooperative multitaskin g 2.         Preemptive multitasking   ·            Co operative multitasking    in cooperative multitasking , program can aquire the cpu for the required amount of time a program canshare CPU with any other program that is executing simultaneously, if it does not currently require the CPU.   ·           Preemptive multitasking . In preemptive multitasking the operating system allocat
Post a Comment
Read more

Batch Processing Operating System

  Batch processing system ·           Batch processing is one of the oldest method    of running the programs ·           The computer in the past were very large in size and their I/O devices were very different from those that are used today. The job processing was not interactive as it is today. ·           The user did not interact directly with computer system.   ·           The process scheduling , memory management, file management and I/Omanagement functions are quite simple in batch processing system   1.         Process scheduling (i.e. allocation strategy for a processor is typically in order of their arrival i.e. first come first served(FCFS)basis.   2.         Memory management  is done by dividing the memoryinto two areas one portion or partition is occupied by resident monitor and the other portionis dynamically used to load the transist program for execution.   3.         I/O management  .since only one program is executed at a time, there is no contention for I/O devic
Post a Comment
Read more