Question

Consider a system where each file is associated with a 16-bit number. For each file, each user should have the read and write capability. How much memory is needed to store each user’s access data?
1. 16 KB
2. 32 KB
3. 64 KB
4. 128 KB

Answer 1

Correct Answer - Option 1 : 16 KB

Answer: Option 1

Explanation: 

The question says that each file is associated with a 16-bit number.

Hence the maximum number of files possible will be 2¹⁶.

for each file, we have to maintain/store access data.

and each user can read or write capability 

we have only 4 possible access data for a particular user 

No Read, No Write

No Read, Write

Read, No Write

Read, Write 

For indicating 4 cases we need only 2 bits for each user.

Hence the total number of bits needed 2 × 2¹⁶ ≡ 2¹⁷ bits

Option 1: 16 KB

16 KB = 16 × 2¹⁰ bytes = 16 × 2¹⁰ × 8 bits = 2¹⁷ bits.

Therefore option 1 is the correct answer: