Memory Management Questions and Answers

Answer: B

Correct answer: is not being used

Internal fragmentation is the space inside an allocated block that the process does not use. It is allocated but wasted, which is what distinguishes it from external fragmentation, where the waste lies between blocks.

Answer: D

Correct answer: single instruction

INPUT NUM is one complete instruction - a command with its operand - so it is a single statement. The line number in front of it is not part of the instruction.

Answer: D

Correct answer: every address generated by the CPU is being checked against the relocation and limit registers

The protection is enforced by hardware on every single memory reference, so no instruction can reach outside its own region however it is written. Being in different address spaces is the consequence of that checking, not the mechanism.

Answer: C

Correct answer: It holds copies of data from main memory that are likely to be used again

Cache holds copies of recently or frequently used data and instructions from main memory, so that repeat accesses are served in a few cycles rather than hundreds. It works because of the principle of locality. Temporal locality means a location just used is likely to be used again shortly; spatial locality means neighbouring locations are likely to be needed next, which is why data is fetched in whole cache lines rather than single bytes. It is faster and smaller than main memory, not slower and larger, so the third option is exactly backwards - it is built from SRAM, which uses several transistors per bit and needs no refreshing, against the single capacitor of DRAM. It is managed entirely by hardware and is transparent to the programmer, unlike main memory, which the operating system allocates, and registers, which the compiler assigns. That transparency is why cache behaviour must be inferred from performance rather than controlled directly. Modern processors use three levels, L1 through L3.

Answer: A

Correct answer: Token

In a token ring only the station holding the token may transmit, and it passes the token on when finished. That is how the topology avoids collisions without any contention.

Answer: A

Correct answer: internal fragmentation occurs

Memory allocated to a process but not used by it is internal fragmentation - the waste lies inside the allocation. External fragmentation is waste between allocations.

Answer: A

Correct answer: each process

Every process has its own page table, which is what makes its address space private: the same page number in two processes maps to different frames.

Answer: B

Correct answer: larger than the hole itself

A hole must be recorded in the free list, and if the hole is very small the record costs more memory than the hole would ever supply. Such holes are therefore left attached to the allocated block, which converts external fragmentation into internal.

Answer: A

Correct answer: integers

Zero, the positive whole numbers and the negative whole numbers together are the integers. Real numbers admit a fractional part, which integers do not.

Answer: A

Correct answer: it is added to the segment base to produce the physical memory address

The logical address is a pair: the segment number selects the entry and the offset says how far into the segment. The physical address is therefore

\[ \text{physical} = \text{base} + d \]

An offset used as a physical address on its own would ignore where the segment actually sits in memory.