Question

(a) A multiplexor has 60 input lines. How many control lines does it need?

(b) A decoder must be designed to select one of 32 circuits. How many input lines does it need?

(c) For the decoder in (b), how many output lines does it need?

Answer 1

a)ans:

In multiplexer

for n control lines a maximum of 2ⁿ inputs is possible.

or

for N inputs lines, log₂ N control lines are required.

for 6 control lines, a maximum of 2⁶ (64)inputs is possible.

so for 60 input lines, 6 control lines are needed.

b)ans:

In decoder

for n input lines, a maximum of 2ⁿ output lines are possible.

or

for N outputs lines, log₂ N input lines are required.

for select one of the 32 circuits , log₂(32) = 5 input lines are needed.

c)ans:

for above 5 input lines a maximum of 2⁵ = 32 outputs lines are needed