Computer Operating System Questions and Answers

Answer: D

Correct answer: multitasking

Running more than one program at a time requires the system software to be capable of multitasking: it must hold several programs in memory, keep each one’s state, and switch the processor between them fast enough that all appear to advance together.

Answer: A

Correct answer: Assembly and output

Turning symbolic labels into actual addresses and emitting the machine instructions is the last phase of compilation - assembly and output. Code generation has already chosen the instructions; this phase fixes their addresses and writes the object module.

Answer: C

Correct answer: gives each task the same chance at the processor

Round robin gives every ready process the same fixed time slice in turn, and a process still running when its slice expires goes to the back of the queue. It is simple to implement and scrupulously fair, but it takes no account of whether a task is interactive or processor-bound.

Answer: B

Correct answer: Systems program

A systems program is concerned with running the machine itself - loading, scheduling, managing files and devices - rather than with the user’s problem. The operating system is the largest example, but assemblers, loaders and utilities belong to the same class. Source and object programs are forms of a user’s own program.

Answer: B

Correct answer: 1

A semaphore guarding a critical section starts at 1: the first process to call wait() takes the count to 0 and enters, and every other process blocks until that one calls signal(). Only one process is inside at a time, which is exactly mutual exclusion.

Answer: A

Correct answer: hold and wait

Coffman’s four conditions are mutual exclusion, no preemption, circular wait and hold and wait - a process holding one resource while waiting for another. All four must hold simultaneously for deadlock, so breaking any one of them prevents it.

Answer: C

Correct answer: VER command

VER displays the version of MS-DOS currently running. DIR lists files, FORMAT prepares a disk, and there is no DISK command for this purpose.

Answer: A

Correct answer: a program or source library

A partitioned data set divides one data set into named members with a directory at its front, so many small units can be stored, listed and fetched by name from a single allocation. That makes it the natural place for a library of source programs, macros or load modules.

Answer: C

Correct answer: Used for address translation

The page map table holds one entry per virtual page, giving the frame it currently occupies together with its valid, referenced and modified bits. The memory management unit consults it on every reference to turn a virtual address into a physical one.

Answer: B

Correct answer: assigning ready process to the CPU

The scheduler decides which process should run next; the dispatcher performs the handover - switching context, restoring the chosen process’s registers and program counter, and giving it the processor. Swapping and paging are the memory manager’s work.