Question

The number of select lines required for an 8-to-1 multiplexer is?

• A. 2
• B. 3
• C. 5
• D. 8

Hint:

The number of select lines determines how many unique inputs can be addressed. With 's' select lines, you can create $2^s$ unique binary combinations, each corresponding to one input line.

Answer 1

The Correct Option is B

A multiplexer (MUX) is a device that selects one of several input lines and forwards it to a single output line.
The relationship between the number of input lines ($m$) and the number of select lines ($s$) is given by the formula:
$m = 2^s$ or equivalently, $s = \log_2 m$.
In this case, we have an 8-to-1 multiplexer, so the number of input lines is $m = 8$.
We need to find the number of select lines, $s$.
Using the formula: $8 = 2^s$.
We know that $2^3 = 8$.
Therefore, the number of select lines required is $s=3$.