Code Converters and Multiplexers - Technical MCQs

Q1:

How many inputs are required for a 1-of-10 BCD decoder?

A 4

B 8

C 10

D 1

ANS:A - 4

The decoder is a combinational circuit that has 'n' input lines and maximum of 2^n output lines.
So, 1-of-10 BCD decoder has n=4 inputs; 2^4 = 16 output lines.
1 Extra line that is for ENABLE signal which is normally active low.