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

Scheduling Algorithms

     Scheduling Algorithms CPU scheduling algorithm deal with the problem of deciding which of the processes in the ready queue is to be allocated the CPU . six commonly used scheduling algorithms are: 1. first-come First-served(FCFS) 2. Shortest job First(SJF) 3. Priority scheduling 4. Round-Robin Scheduling(RR) 5. Multi-Level Queue Scheduling(MLQ) 6. Multi-Level Feedback Queue Scheduling (MFQ)       First-Come First-Served Scheduling (FCFS) ·       It is simplest and the most straight forward of all scheduling algorithms. ·       In this scheduling, the process that request the CPU first is allocated CPU first. Thus   the name first come first served. ·       We can say that in FCFS scheduling, a process is allocated CPU time according to the arrival time of a process. ·       The implementation of FCFS policy is easily manged with a FIFO queue...
Post a Comment
Read more

Time Sharing System and its Requirements

  Time sharing  system ·           Time sharing refers to the allocation of computer resources in a time dependent fashion to several program simultaneously ·           A time sharing system has many user terminals that are connected to same computer simultaneously. Using these terminal, different users can work on a system at the same time ·           Thus, it uses multi programming with a special CPU scheduling among all the last one, and then again beginning from the first one ·           In time sharing system, the CPU time is divided among all the users on schedule basis. ·           It release the CPU under any of the following three conditions: 1.         When the allotted time slice expires. 2.    ...
Post a Comment
Read more

What is RAM and Why is it Important?

  What is RAM and Why is it Important? Random access memory (RAM) is a computer's short-term memory. None of your programs, files, or Netflix streams would work without RAM, which is your computer’s working space. But what is RAM exactly? In this article, we explain what RAM means in computer terms and why it’s important. What does RAM stand for? RAM is short for “random access memory” and while it might sound mysterious, RAM is one of the most fundamental elements of computing. RAM is the super-fast and temporary data storage space that a computer needs to access right now or in the next few moments. What is RAM and Why is it Important? Random access memory (RAM) is a computer's short-term memory. None of your programs, files, or Netflix streams would work without RAM, which is your computer’s working space. But what is RAM exactly? In this article, we explain what RAM means in computer terms and why it’s important. What does RAM stand for? RAM is short for “random access memo...
Post a Comment
Read more

Multi user Operating System

  Multi user operating system ·           In a multi-user operating system, multiple number of user can access different resources of a computer at a same time. ·           The access is provided using a network that consists of various personal computer attached to a mainframe computer system.                                                              diagram of multi -user operating system       ·           The various personal computer can send and receive information to mainframe computer system. ·           The example    of multi-user OS are UNIX, windows 2000,novell netware.            sing...
Post a Comment
Read more

System structure operating architecture

  System structure operating  architecture An operating system is a construct that allows the user application programs to interact with the system hardware. Since the operating system is such a complex structure, it should be created with utmost care so it can be used and modified easily. An easy way to do this is to create the operating system in parts. Each of these parts should be well defined with clear inputs, outputs and functions. Simple Structure There are many operating systems that have a rather simple structure. These started as small systems and rapidly expanded much further than their scope. A common example of this is MS-DOS. It was designed simply for a niche amount for people. There was no indication that it would become so popular. An image to illustrate the structure of MS-DOS is as follows − It is better that operating systems have a modular structure, unlike MS-DOS. That would lead to greater control over the computer system and its various applications. T...
Post a Comment
Read more