Computer Operating System Questions and Answers

Answer: A

Correct answer: Is run after config.sys on system boot-up

AUTOEXEC.BAT is a batch file of ordinary commands, so it can only run once COMMAND.COM has been loaded - which happens after CONFIG.SYS has been read and its drivers installed. That is why drivers go in CONFIG.SYS and commands such as PATH and SET go in AUTOEXEC.BAT.

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: D

Correct answer: MS DOS

MS-DOS is single-tasking: it runs one program at a time and has no scheduler, which is why background behaviour had to be faked with terminate-and-stay-resident tricks. Windows 98, NT and XP all schedule several processes genuinely concurrently.

Answer: B

Correct answer: MEM

MEM reports how memory is being used - conventional, upper, extended and expanded - and how much of each is free. CHKDSK reports on the disk, and MEMMAKER rearranges drivers to free conventional memory rather than reporting on it.

Answer: A

Correct answer: allows the programmer to write base registers and displacements explicitly in the source program

The System/370 addresses memory as a base register plus a displacement, and its assembler language lets the programmer write both explicitly - or leave the assembler to supply them from a USING declaration. That control over addressing is characteristic of the language.

Answer: B

Correct answer: Mode LPT1=COM1

MODE LPT1=COM1 redirects output sent to the first parallel port so that it goes to the first serial port instead, which is what allows a program that only knows how to print to LPT1 to drive a serial printer. The serial line’s speed and parity are set with a separate MODE command.

Answer: B

Correct answer: consists of those addresses that may be generated by a processor during execution

The virtual address space is the whole set of addresses a program may generate, which is fixed by the width of the address field rather than by how much physical memory exists. Address translation maps the part in use onto real frames; the rest lives on disk.

Answer: A

Correct answer: CMOS

A virus infects things that are read as programs or as file data - the boot sector, program files, the contents of floppies. The CMOS holds only the setup values (date, drive types, boot order) and is never executed, so a virus has nothing to infect there.

Answer: B

Correct answer: Optimal

The optimal algorithm replaces the page that will not be needed for the longest time ahead, which requires knowing the future reference string. It cannot be implemented, but it serves as the benchmark against which FIFO and LRU are measured.

Answer: B

Correct answer: terminate and stay resident program

A TSR returns control to DOS but leaves its code in memory, normally with an interrupt vector pointing into it, so it can be re-entered by a hot key or by the hardware event it services. It was the only way to get background behaviour out of a single-tasking system.