Q. What are parallel and multi-programmed batched systems? What are the differences between parallel and multi-programmed batched systems?
Multi-programmed Batched Systems:
In multi-programmed batched operating systems, the operating system reads jobs from disk drives where a list of jobs are already being stored through card readers. The operating system then pull and store as much job as it can in the memory. Then from the memory, operating system start working on a job. Now, whenever a job reaches a situation where is has to be waiting for one or more tasks to be completed like use of any IO devices, the operating system pulls another job from the memory and starts working on it. Whenever this job also starts waiting, for example it need to use the same IO which is already in use by its previous job, the operating systems pulls another job. This is how, a multi-programmed batched systems harness the power of disk drives and memory.
Parallel Systems:
Parallel operating systems (also tightly coupled systems) are supposed to be used in machines with more than one processor connected closely where these multiple processors will be sharing memory, clock, buses and other peripherals. Parallel systems are designed to distribute a job to multiple processors to have faster speed. But the speed-ratio is for n processor is not n the times for a single processor. As, when multiple processors cooperate on a task, a certain amount of overhead is incurred in keeping all the parts working correctly. Different model of parallel systems exists, such as symmetric-multiprocessing model where each processors runs a copy of the operating system, these operating systems communicate each other when required. Another model is asymmetric-multiprocessing where each processors get a specific task to do. A master processor controls other processors and maintain the workflow. This is a master-slave situation where slaves’ checkout for tasks from masters or sit idle.
Differences Between Parallel and Multi-programmed Batched Systems:
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Parallel Systems
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No.
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Multi-programmed Batched Systems
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System that operates on a machine with 2 or more processors.
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1
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System that can run 2 or more processes at a time is multi-programmed batched systems.
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This system is dependent on processors. That is all processors can complete segments of a single task or can be processing different processes.
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2
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This system depends on devices. That is, it depends on devices to switch between tasks such I/O interrupts etc.
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Example: Unix, Linux etc.
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3
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Example: Windows 95, MacOS etc.
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