Computer Operating System Questions and Answers

Answer: C

Correct answer: critical section

The critical section is the part of a program that accesses the shared resource, and it must be executed indivisibly - no other process may be in its own critical section for the same resource at the same time. Semaphores and other mechanisms exist to enforce that.

Answer: A

Correct answer: actually schedules the tasks into the processor

The scheduler decides which process should run next; the dispatcher is the module that carries that decision out - switching context, restoring the chosen process’s registers, and handing it the processor. It is on the critical path of every context switch, so its speed matters.

Answer: D

Correct answer: DOS=UMB

DOS=UMB in CONFIG.SYS tells DOS to take charge of the upper memory blocks that EMM386 has made available, so that DEVICEHIGH= and LOADHIGH then have somewhere to put drivers and TSRs. Without it those two commands silently load low.

Answer: B

Correct answer: Manages the use of extended memory

HIMEM.SYS is the extended memory manager: it arbitrates access to memory above 1 MB and provides the high memory area. EMM386 is the one that emulates expanded memory.

Answer: D

Correct answer: All of the above

MS-DOS, PC-DOS and Unix are all operating systems, and an operating system is the central piece of system software - the layer that manages the processor, memory, files and devices so that applications need not. All three have run on microcomputers.

Answer: C

Correct answer: MODE CO40

MODE CO40 sets the display to colour with 40 columns - CO for colour, 40 for the column count. The companion settings are CO80, BW40, BW80 and MONO.

Answer: D

Correct answer: all of the above

A macro processor must do all three: recognise macro definitions and calls in the source, save each definition where it can be found again, and at every call expand the saved body, substituting the actual arguments for the formal parameters. Omitting any one leaves the facility unusable.

Answer: C

Correct answer: worst fit

Worst fit deliberately places a request in the largest free hole, on the reasoning that the remainder left over will still be big enough to be useful, whereas best fit leaves a scatter of slivers too small for anything. First fit simply takes the first hole large enough.

Answer: A

Correct answer: block

A process moves itself from running to blocked by asking for something not yet available - an input operation, or a semaphore held by another process. That transition is the one the process initiates. Dispatch, timer run-out and wake-up are all imposed on it by the scheduler or by another process.

Answer: D

Correct answer: type c:\autoexec.bat|more.

Piping the output of TYPE into MORE makes it stop at the end of each screenful and wait for a key. TYPE itself has no pause switch, so the pipe to the MORE filter is what provides it.