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## Operating systems MCQ Set - 3

1. The memory map of a multithreaded process looks similar to that of a single threaded process except that the multithreaded one has
a. a copy of the data segment per thread.
b. a stack for each thread.
c. a heap for each thread.
d. a heap and stack for each thread
 Answer: Each thread requires a separate stack to be allocated for it (from the memory that is shared among all threads).

2. In a thread-aware operating system, a process control block (PCB) no longer includes
a. saved registers.
b. process owner.
c. open files.
d. memory map.
 Answer: Since each thread has its own register set, the registers have to be saved per thread in the Thread Control Block (TCB). The owner, process memory, and open files are shared among all threads in a process so they can still be tracked in the Process Control Block.

3. Inverted page tables are
a. Faster than regular page tables
b. Smaller than regular page tables
c. More flexible than regular page tables
d. None of the above
 Answer: Contains one entry per physical frame as opposed to one for each virtual page as in the case of standard page tables. This makes it much smaller compared to standard page tables.

4. Assume three jobs arrive at approximately the same time, but Job A arrives slightly before Job B, and Job B arrives slightly before job C. Job A requires 2 sec of CPU, Job B is 8 secs, and Job C is 7 secs. Assume a time-slice of 1 sec. Given a FIFO scheduler, what is the turnaround time of job B?
a. 0 seconds
b. 2 seconds
c. 8 seconds
d. 10 seconds
 Answer: FIFO: A (until 2), B (until 10), C (until 17); B completes at time 10 seconds.

5. Consider a disk with the following characteristics; Find the number of heads for this disk.
• Number of surfaces: 8 (= 23)
• Number of tracks / surface: 512 K (= 219)
• Number of bytes / track: 8 MB (= 223 bytes)
• Number of sectors / track: 8 K (= 213)
• On-disk cache: 16 MB (= 224 bytes)
a. 1
b. 2
c. 4
d. 8

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