Computer Knowledge

Computer Memory and Storage

2,477 Questions

Computer memory and storage questions test foundational knowledge of hardware, cache mapping, and data transfer mechanisms. Key areas include Direct Memory Access, analog recording, and RAID levels. This section is essential for candidates preparing for banking and government computer proficiency tests.

Cache memory mappingDirect memory accessRAID storage levelsHard disk technologyOptical media storageMemory addresses

Computer Memory and Storage Questions

Multiple choice

A computer system has an L1 cache, an L2 cache, and a main memory unit connected as shown below. The block size in L1 cache is 4 words. The block size in L2 cache is 16 words. The memory access times are 2 nanoseconds, 20 nanoseconds and 200 nanoseconds for L1 cache, L2 cache and main memory unit, respectively.

When there is a miss in L1 cache and a hit in L2 cache, a block is transferred from L2 cache to L1 cache. What is the time taken for this transfer?

  1. 2 nanoseconds

  2. 20 nanoseconds

  3. 22 nanoseconds

  4. 88 nanoseconds
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Memory access time for L1 = 2 ns. Memory access time for L2 = 20 ns. Memory access time for L3 = 200 ns. If there is a miss in L1, then transfer will go to L2. So, total time in this transfer = 20 + 2 = 22 ns. The block size in L1 = 4 words. So, the time taken in transfer from L2 to L1 = 22 * 4 = 88 ns. So, this option is correct.

Multiple choice

A computer system has an L1 cache, an L2 cache, and a main memory unit connected as shown below. The block size in L1 cache is 4 words. The block size in L2 cache is 16 words. The memory access times are 2 nanoseconds. 20 nanoseconds and 200 nanoseconds for L1 cache, L2 cache and main memory unit respectively.

When there is a miss in both L1 cache and L2 cache, first a block is transferred from main memory to L2 cache, and then a block is transferred from L2 cache to L1 cache. What is the total time taken for these transfers?

  1. 222 nanoseconds

  2. 888 nanoseconds

  3. 902 nanoseconds

  4. 968 nanoseconds
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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Multiple choice

To copy system files on the disk in target disk, we use

  1. copy

  2. move

  3. sys

  4. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The SYS command (in DOS/Windows) is used to copy system files (IO.SYS and MSDOS.SYS in DOS) to a target disk to make it bootable. The copy command copies regular files, move transfers files, and the sys command specifically handles hidden system files needed for booting.

Multiple choice

Which of the following is used to write disk block images from memory to disk?

  1. clri

  2. sync

  3. mkfs

  4. stty
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sync keeps all the information in the core memory that should be on disk to be written out. This contains modified i-nodes, modified super blocks and delayed input output block.This should be used by programs which examine the file system. It is mandatory before a boot Synopsis:sync()

Multiple choice

In which block is available free inode number found?

  1. Boot block

  2. Super block

  3. Inode block

  4. Data blocks
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The super block contains information about the entire disk and the I-node list -a list of inodes. The super block also contains an array to represent free inodes.

Multiple choice

Consider a hypothetical processor with an instruction of type LW R1, 20(R2), which during execution reads a 32-bit word from memory and stores it in a 32-bit register R1. The effective address of the memory location is obtained by the addition of constant 20 and the contents of register R2. Which of the following best reflects the addressing mode implemented by this instruction for the operand in memory?

  1. Immediate Addressing

  2. Register Addressing

  3. Register Indirect Scaled Addressing

  4. Base Indexed Addressing
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Here, 20 will act as base and content of R2 will be index.

Multiple choice

An application loads 100 libraries at startup. Loading each library requires exactly one disk access. The seek time of the disk to a random location is given as 10 ms. Rotational speed of disk is 6000 rpm. If all 100 libraries are loaded from random locations on the disk, how long does it take to load all libraries? (The time to transfer data from the disk block once the head has been positioned at the start of the block may be neglected)

  1. 0.50 s

  2. 1.50 s

  3. 1.25 s

  4. 1.00 s
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

6000 rotations ________ 60 sec 1 rotation ________10 ms $\therefore$Rotational latency = 5 ms Time for one disk access = 15 ms Time to load all libraries = 15×100 = 1500 ms = 1.5 sec

Multiple choice

Register renaming is done is pipelined processors

  1. as an alternative to register allocation at compile time

  2. for efficient access to function parameters and local variables

  3. to handle certain kinds of hazards

  4. as part of address translation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Register renaming is done to eliminate WAR/WAW hazards.