Memory Management Questions and Answers

Answer: B

Correct answer: it helps to reduce the size of page table needed to implement the virtual address space of a process

A single-level table needs an entry for every page whether or not it is used, which for a large address space is enormous. A multilevel table pages the table itself, so only the parts actually in use need exist. It does not make access faster - each level is another memory reference.

Answer: A

Correct answer: program counter

The program counter holds the address of the next instruction, and the fetch cycle begins by sending its contents to memory. The instruction register receives what comes back.

Answer: B

Correct answer: cache

A cache sits between two levels working at different speeds - processor and memory, or memory and disk - and holds recently used items so the faster side need not wait for the slower one.

Answer: C

Correct answer: logical address

Every address a program generates is a logical, or virtual, address; the memory management unit translates it into the physical address that reaches the memory chips.

Answer: A

Correct answer: memory management unit

The MMU is the hardware that performs the translation on every reference, using the page or segment tables. Doing it in hardware is what makes virtual memory affordable.

Answer: B

Correct answer: paging

Paging moves fixed-size pages between disk and main memory as they are needed, so a process may run with only part of itself resident.

Answer: B

Correct answer: page table base register

The page table base register holds the address of the current process's page table, so a context switch need only reload that one register.

Answer: A

Correct answer: logical address

A program refers only to logical addresses; it never sees where in physical memory it has actually been placed, which is what allows it to be moved or paged.

Answer: A

Correct answer: base address of each page in physical memory

Each page table entry gives the frame the page occupies, that is the base address of that page in physical memory. The offset is carried through unchanged and is not stored.

Answer: C

Correct answer: a technique for overcoming external fragmentation

Compaction shuffles the allocated blocks together so that the scattered free holes merge into one. It does nothing about internal fragmentation, which is waste inside an allocation.