GATE CSE 2002 | Question: 2.21

Question

Which combination of the following features will suffice to characterize an OS as a multi-programmed OS?

1. More than one program may be loaded into main memory at the same time for execution
2. If a program waits for certain events such as I/O, another program is immediately scheduled for execution
3. If the execution of a program terminates, another program is immediately scheduled for execution.

• A. (a)
• B. (a) and (b)
• C. (a) and (c)
• D. (a), (b) and (c)

Comments

a should be correct. The word "immediately" in point b raises doubt on option b.If there are n process and all are doing I/O simultaneously,then how will CPU cannot immediately schedule the new process.

Or if one process goto I/O ,then selecting the another process to run ,may take time,it cannot be done immediately.

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@Rahul

a) alone does not suffice multiprogramming environment, lets suppose you load MM with sufficient number of processes but whenever some process go for i/o, processor waits until that process does not complete its i/o, this scenario does not resemble multiprogramming enviorement

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You are correct.Thanks.But will it schedule other process immediately?This is concerning me

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D will be correct choice

Answer 1

In batch processing processes halt in between executions and and there is no preemptive scheduling.So option d.

Comments

1. More than one program may be loaded into main memory at the same time for execution: I think this point is also common for every os as ready state is in main memory and it may contains all the process require to be executed.

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@rajatmyname i am also thinking like you so what will be correct option can any one can justify the answer