edited by
6,478 views
4 votes
4 votes

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
edited by

3 Answers

11 votes
11 votes
I think answer is A .

Question is that how much memory is needed to store each user's access data so its only the memory reqd for read/write information  which is asked. For 2^16 files, there are 4 different combinations of read(R) write(W). Read, write, no read, no write.

So bits reqd for 1 file to store access info=2

Bits reqd for 2^16 files=(2^16)×2 bits=128Kb

Converting this bits into bytes we get 128Kb/(8bits/Byte)

=16KB
5 votes
5 votes
Files are associated with 16 bit number.

=> File ID ranges from 0000 0000 0000 0000 to 1111 1111 1111 1111.

=> Total File IDs possible = Total files possible = $2^{16}$

 

For each user, we need 2 bits. 1 bit for read (0 => can't read; 1 => can read)

and 1 bit for write (0=> can't write; 1 => can write)

 

So, $2^{16}*2bits$  =  $2^{16}*2/8bytes$  =  $2^{14} bytes$  =  $16KB$
4 votes
4 votes
i think answer will be a. plz post the answer if correct. total number of files by 16 bit number will be 2^16 and assuming 2 bit for read and write as permission can be no read no write no read but write .... so on 4 cases . 2 bit for that . and the user will have these 2 byte for all the files so 2^16*2=128Kbit

128/8=16kB
Answer:

Related questions

8 votes
8 votes
3 answers
1
go_editor asked Jul 1, 2016
4,647 views
Which of the following is not an optimization criterion in the design of a CPU scheduling algorithm?Minimum CPU utilizationMaximum throughputMinimum turnaround timeMinimu...
4 votes
4 votes
4 answers
2
go_editor asked Jul 1, 2016
5,595 views
Dirty bit is used to indicate which of the following?A page fault has occurredA page has corrupted dataA page has been modified after being loaded into cacheAn illegal ac...
9 votes
9 votes
3 answers
3
go_editor asked Jul 1, 2016
6,475 views
What is the minimum number of resources required to ensure that deadlock will never occur, if there are currently three processes $P_1, P_2$ and $P_3$ running in a system...
4 votes
4 votes
3 answers
4