Phrases Previous Year Questions (PYQs) – Computer Memory Back-up Devices – Page 1 of 2

✅ Conversion (Using Powers of 2):

• 1 Terabyte (TB) = $2^{10}$ Gigabytes (GB)
• 1 Exabyte (EB) = $2^{10}$ Petabytes (PB)
• 1 Petabyte (PB) = $2^{10}$ Terabytes (TB)
• Therefore, 1 Exabyte (EB) = $2^{10}\times 2^{10}\times 2^{10}=2^{30}$ Gigabytes (GB)

✅ Final Answer:

• 1 Terabyte (TB) = $\boxed{{\displaystyle 2^{10}}}$ GB
• 1 Exabyte (EB) = $\boxed{{\displaystyle 2^{30}}}$ GB

✅ Concept:

The fastest means of memory access for the CPU refers to the storage that allows the quickest retrieval of data. This is crucial for efficient processing and performance.

✅ Explanation of Options:

• Registers: Registers are the fastest form of memory access because they are directly in the CPU. However, they are very small and not used for regular memory storage.
• Cache: Cache memory is the most effective and frequently used type of memory, as it stores frequently accessed data for fast retrieval. It is still slower than registers but much faster than main memory.
• Main Memory: Main memory (RAM) is slower than both cache and registers, but it provides larger storage for currently active processes.
• Stack: The stack is used for storing function calls and local variables. While it is quick, it still doesn't surpass cache memory in terms of speed.

✅ Final Answer:

The fastest means of memory access for the CPU is $\boxed{{\displaystyle \text{Registers}}}$.

✅ Given Values:

• Memory Access Time: 10 milliseconds
• Cache Hit Ratio: 15% = 0.15

✅ Formula for Effective Memory Access Time (EMAT):

$\text{EMAT}=\text{Cache Hit Ratio}\times \text{Cache Access Time}+(1-\text{Cache Hit Ratio})\times (\text{Memory Access Time}+\text{Cache Access Time})$

✅ Step 1: Plug Values into the Formula:

$\text{EMAT}=0.15\times 10+(1-0.15)\times (10+10)$

$\text{EMAT}=0.15\times 10+0.85\times 20$

$\text{EMAT}=1.5+17$

$\text{EMAT}=18.5\text{milliseconds}$

✅ Final Answer:

EMAT = 18.5 milliseconds

Solution:

Given Question:
Which of the following statements is wrong related to FAT32 and NTFS?

Option Analysis:
1) Read and write speeds of NTFS are faster than that of FAT32 — ✅ Correct
2) FAT32 has lower disk utilisation compared to NTFS — ✅ Correct
3) NTFS stands for New Technology File System — ✅ Correct
4) FAT32 stores individual files of size up to 32 GB — ❌ Incorrect

Explanation:
FAT32 has a maximum file size limit of 4 GB, not 32 GB. So, option 4 is factually wrong.

Final Answer:
Option 4 — FAT32 stores individual files of size up to 32 GB is wrong.

Data Flow Management

Question:
What is the name of the storage device that compensates the difference in rates of flow of data from one device to another?

✅ Correct Answer: Buffer

Explanation:

A Buffer is a temporary storage area that helps in matching the speed of data transfer between a fast and a slow device, ensuring smooth data flow without loss.

Final Answer: Buffer

Quick Solution

Each RAM chip: 32K × 1 = 32K bits = 4 KB

Total required: 256 KB

Number of chips needed: 256 ÷ 4 = 64

✅ Final Answer: 64 chips

Data Transfer Interface in Computer Systems

Question: Which interface transfers data between memory and I/O peripheral without CPU involvement?

✅ Correct Answer: Direct Memory Access (DMA)

Why DMA?

• The CPU only initiates the process.
• The DMA controller directly transfers data between I/O and memory.
• Frees the CPU for other tasks, improving efficiency.

❌ Incorrect Options (if any): Programmed I/O, Interrupt-driven I/O – both require CPU involvement.