Memory Hierarchy Questions and Answers

Answer: A

Both statements are true. RAM is volatile memory, which loses its contents when power is switched off, and it has a limited storage capacity. Secondary memory is the storage other than RAM and ROM, such as hard disks, and it keeps data permanently. Marking either statement as false would be wrong, so the first option is correct. RAM is the main working memory of the computer, and secondary memory such as a hard disk or an SSD is where files are kept when the power is off.

Answer: C

The starting addresses are (0, 8, 16, 24).

Each block is selected by IA4 and IA3 through the decoder: IA4 IA3 = 00 enables X1, 01 enables X2, 10 enables X3 and 11 enables X4. The other ten lines (IA11 to IA5 and IA2 to IA0) form the address inside the block. The starting location of a block, Addr = 0, has all ten of those lines at 0, so only IA4 and IA3 can be 1:

\[ \begin{aligned} X1&: 0,\quad X2: 2^{3} = 8 \\ X3&: 2^{4} = 16,\quad X4: 2^{4} + 2^{3} = 24 \end{aligned} \]

(0, 1024, 2048, 3072) is what the usual design gives, with the two top lines IA11 and IA10 on the decoder; here the decoder sits on bits 4 and 3. (0, 1, 2, 3) would need IA1 and IA0 on the decoder. The four blocks cannot all start at address 0, because each address enables exactly one block.

Answer: D

All three are memory performance parameters, so the answer is (i), (ii) and (iii).

William Stallings gives three performance parameters for memory: access time (latency), the time to perform a read or write; memory cycle time, the access time plus any further time before a second access can start; and transfer rate, the rate at which data can be moved into or out of the memory unit.

Each option that leaves one of them out is therefore incomplete.