Computer Operating System Questions and Answers

Answer: C

Correct answer: only the active pages of a program are stored in primary storage

Virtual storage keeps only the pages a program is currently using in main memory and leaves the rest on disk, fetching each as it is referenced. A program can therefore be larger than the memory available, and the memory can be shared among more programs than would otherwise fit.

Answer: D

Correct answer: all of the above

Building the macro processor into pass 1 of the assembler avoids implementing input, output and table handling twice, avoids writing an intermediate file between the two programs, and gives the programmer more flexibility, since macro definitions and assembler statements may be interleaved freely. All three advantages follow from the merge.

Answer: B

Correct answer: 2

Dekker’s algorithm was the first correct software solution to mutual exclusion, and it works for exactly two processes. It combines two intention flags with a turn variable, so that when both want to enter the turn variable breaks the tie and neither can be starved. Generalising it to \( n \) processes needed Dijkstra’s and later Lamport’s work.

Answer: C

Correct answer: allows each program in turn to use the memory

Swapping moves a whole process out to backing store and brings another in, so the processes take turns occupying memory rather than sharing it at the same instant. It is the coarsest form of memory management, and it is what paging refines by moving pages rather than whole processes.

Answer: C

Correct answer: Program

A program is the sequence of instructions, written in a computer language, that produces the desired result when executed. An algorithm is the method it implements, expressed independently of any language, and a decision table sets out conditions and actions as a design document.

Answer: C

Correct answer: Mode

MODE redirects printer output from a parallel port to a serial one - MODE LPT1=COM1 - and also sets the serial line’s baud rate, parity and stop bits. PRINT queues files for printing but does not redirect the port.

Answer: D

Correct answer: All of the above

The paging software does all three: it implements each program’s address environment, mapping virtual pages to frames; it manages the physical address space, deciding which frames are occupied and which page to evict; and it enforces sharing and protection, letting two processes map the same frame while denying access outside their own pages.

Answer: D

Correct answer: as several incrementals, followed by an image copy

The economical scheme is a series of incremental backups, each copying only what changed since the last, followed periodically by a full image copy that resets the chain. Incrementals are quick and small; the image copy limits how many tapes a restore has to walk through.

Answer: B

Correct answer: spooling

Spooling - simultaneous peripheral operation on line - writes output destined for a slow device to a disk queue instead, and a separate process feeds it to the device later. The program is freed at once rather than being held back to the speed of the printer, and several jobs' output can be interleaved fairly.

Answer: B

Correct answer: they are initially stored on disk

These systems are called disk operating systems because the system itself lives on disk and is loaded from there when the machine starts, rather than being held permanently in ROM as the earlier microcomputer monitors were. Managing files on disk was their central new capability.