Computer Engineering GATE-2012 detailed solutions

1)  The simplified SOP (Sum of Product) form of the Boolean expression (P + Q(dash) + R).(P + Q(dash) + R).(P + Q + R(dash)) is 

(A) (P(dash)Q + R(dash))     (B) (P + (QR)(dash))     (C) (P(dash)Q + R)     (D) (PQ + R)

Ans) 

1

 f = (P + R(dash)) (P + Q(dash))

           = P + (QR)(dash)

Hence (B) is correct option.

2)  Which one of the following circuits is NOT equivalent to a 2-input XNOR

(exclusive NOR) gate?

2

Ans)  All options except option ‘D’ gives EX-NOR gates

Hence (D) is correct option.

3)The minimum number of D flip-flops needed to design a mod-258 counter is

(A) 9      (B) 8      (C) 512      (D) 258

Ans)  2n  ³ 258 Þ n = 9

Hence (A) is correct option.

4)  A thread is usually defined as a ‘light weight process’ because an operating

system (OS) maintains smaller data structures for a thread than for a process. In

relation to this, which of the followings is TRUE?

(A) On per-thread basis, the OS maintains only CPU register state

(B) The OS does not maintain a separate stack for each thread

(C) On per-thread basis, the OS does not maintain virtual memory state

(D) On per thread basis, the OS maintains only scheduling and accounting

information

Ans)  (A) is correct option.

5)  K4 and Q3 are graphs with the following structures

5

Which one of the following statements is TRUE in relation to these graphs?

(A) K4 is planar while Q3 is not       (B) Both K4 and Q3 are planar

(C) Q3 is planar while K4 is not       (D) Neither K4 not Q3 is planar

Ans)  Both K4 and Q3 are planar

Hence (B) is correct option.