Logic System Design

The minimum number of 2-input NAND gates required to implement a 2-input XOR gate is

• 4

• 5

• 6

• 7

In the circuit shown, diodes and are ideal, and the inputs and are “0 V” for logic ‘0’ and “10 V” for logic ‘1’. What logic gate does the circuit represent?

• 3-input OR gate

• 3-input NOR gate

• 3-input AND gate

• 3-input XOR gate

Consider a four bit D to A converter. The analog values corresponding to digital signals of values 0000 and 0001 are 0 V and 0.0625 V, respectively. The analog value (in Volts ) corresponding to the digitals signal 1111 is ______________

• 0.93

• 0.95

• 0

• 1

In a DRAM

• Periodic refreshing is not required

• Information is stored in a capacitor

• Information is stored in a latch

• Both read and write operations can be performed simultaneously

The Boolean expression in fig simplifies to

• X

• Y

• XY

• X+Y

Consider a Boolean gate (D) where the output Y is related to the inputs A and b as, Y = A + ^B, where + denotes logical OR operation. The Boolean inputs '0' and '1' are also available separately. Using instances of only D gates and inputs '0' and '1', ___________

• NAND & NOR can be implemented

• OR can be implemented

• AND can be implemented

• NOT can be implemented

Consider the 2-bit multiplexer (MUX) shown in the figure. For OUTPUT to be the XOR of C and D, the values for A₀, A₁, A₂ and A₃ are ___________.

• A₀ = 0, A₁ = 0, A₂ = 1, A₃ = 1

• A₀ = 1, A₁ = 0, A₂ = 1, A₃ = 0

• A₀ = 0, A₁ = 1, A₂ = 1, A₃ = 0

• A₀ = 1, A₁ = 1, A₂ = 0, A₃ = 0

A state transition diagram with states A, B, and C, and transition probabilities p₁, p₂, ....., p₇ is shown in the figure (e.g., p₁ denotes the probability of transition from state A to B). For this state diagram, select the statements which is/are universally true.

• p2+p3=p5+p6

• p2+p3=p4+p6

• p2+p5+p6=1

• p2+p3+p5+p6=1

What input should be given to “S” when SR flip – flop is converted to JK flip – flop?

• K.^Q

• K.Q

• J.Q

• J.^Q

What value is to be considered for a “don’t care condition”?

• 0

• 1

• Either 0 or 1

• Any number except 0 and 1