ISRO CS 2007

Question 31

Consider a computer system that stores a floating-point numbers with 16-bit mantissa and an 8-bit exponent, each in two’s complement. The smallest and largest positive values which can be stored are

• 1 × 10 ^-128and 2¹⁵× 10¹⁵
• 1 × 10 ^-256and 2¹⁵× 10²⁵⁵
• 1 × 10 ^-128and 2¹⁵× 10¹²⁷
• 1 × 10 ^-128and 2¹⁵- 1 × 10¹²⁷

Question 32

In comparison with static RAM memory, the dynamic Ram memory has

• lower bit density and higher power consumption
• higher bit density and higher power consumption
• lower bit density and lower power consumption
• higher bit density and lower power consumption

Question 33

The Hexadecimal equivalent of 01111100110111100011 is

• CD73E
• ABD3F
• 7CDE3
• FA4CD

Question 34

Disk requests are received by a disk drive for cylinder 5, 25, 18, 3, 39, 8 and 35 in that order. A seek takes 5 msec per cylinder moved. How much seek time is needed to serve these requests for a Shortest Seek First (SSF) algorithm? Assume that the arm is at cylinder 20 when the last of these requests is made with none of the requests yet served

• 125 msec

• 295 msec

• 575 msec

• 750 msec

Question 35

A task in a blocked state

• is executable
• is running
• must still be placed in the run queues
• is waiting for some temporarily unavailable resources

Question 36

Semaphores

• synchronize critical resources to prevent deadlock
• synchronize critical resources to prevent contention
• are used to do I/O
• are used for memory management

Question 37

On a system using non-preemptive scheduling, processes with expected run times of 5, 18, 9 and 12 are in the ready queue. In what order should they be run to minimize wait time?

• 5, 12, 9, 18
• 5, 9, 12, 18
• 12, 18, 9, 5
• 9, 12, 18, 5

Question 38

The number of page frames that must be allocated to a running process in a virtual memory environment is determined by

• the instruction set architecture
• page size
• number of processes in memory
• physical memory size

Question 39

A program consists of two modules executed sequentially. Let f₁(t) and f₂(t)respectively denote the probability density functions of time taken to execute the two modules. The probability density function of the overall time taken to execute the program is given by

• f₁(t) + f₂(t)
• ∫^t₀f₁(x), f₂(x) dx
• ∫^t₀f₁(x), f₂(t - x) dx
• max (f₁(t), f₂(t))

Question 40

Consider a small 2-way set-associative cache memory, consisting of four blocks. For choosing the block to be replaced, use the least recently (LRU) scheme. The number of cache misses for the following sequence of block addresses is 8, 12, 0, 12, 8

• 2
• 3
• 4
• 5