Operating System

note!Answer: A) Deltree
DELTREE deletes a directory along with all its files and subdirectories.

note!Answer: C) Defrag
DEFRAG rearranges fragmented file pieces so they are stored contiguously, improving disk performance.

note!Answer: C) Sys
SYS copies the hidden system files (IO.SYS, MSDOS.SYS) and COMMAND.COM to another disk.

note!Answer: B) 255 character
Windows allows long file names up to 255 characters (the 8-character limit was the old DOS 8.3 format).

note!Answer: D) Any of the above
A busy process, high I/O rates, and high paging rates can each slow response time. Any of them can therefore cause it.

note!Answer: A) Number of programs processed by it per unit time
Throughput is the number of jobs or programs a system completes per unit of time. It is a standard measure of system performance.

note!Answer: C) The number of logical records in one physical record
The blocking factor is how many logical records fit into one physical block. It determines how efficiently I/O is used.

note!Answer: C) Round-Robin.
Round-Robin gives each process a fixed time slice in turn, which suits interactive time-sharing. The other policies do not give fair, responsive time slices.

note!Answer: A) 4.
With n processes each needing m units, deadlock is avoided when total units = n(m−1)+1 = 3(2−1)+1 = 4.

note!Answer: B) is likely to be the one of the pages used in the last few page references.
Locality of reference means that recently used pages are likely to be referenced again soon.

note!Answer: A) Structured into two halves called top half and bottom half
UNIX device drivers are divided into a top half (called from processes) and a bottom half (interrupt handling).

note!Answer: C) RU policy (Recurrently used)
LRU, FIFO and Optimal are standard page replacement policies; 'RU' is not one.

note!Answer: C) 70000
The relocation register holds the actual start address of the allocated memory, which is 70000.

note!Answer: B) Long term scheduler.
The long term (job) scheduler selects jobs from secondary storage and loads them into memory. The short term scheduler picks from the ready queue.

note!Answer: B) Shortest job first Scheduling
Shortest Job First (SJF) gives the CPU to the process with the smallest next CPU burst.

note!Answer: A) time since its submission to the time its results become available.
Turnaround time is the interval from submission of a job to the availability of its results.

note!Answer: A) forced de allocation of the CPU from a program which is executing on the CPU.
Preemption means the operating system forcibly takes the CPU away from a running process.

note!Answer: C) Least Recently Used.
LRU (Least Recently Used) replaces the page that has not been used for the longest time.

note!Answer: D) None of the above
Reliability, incremental growth and resource sharing are all advantages of distributed systems, so none is excluded.

note!Answer: A) Dynamic Data Exchange
DDE stands for Dynamic Data Exchange, a Windows mechanism for sharing data between applications.