Question

Assume a 8x1 multiplexer’s data inputs have the following present values: i0=0, i1=0, i2=0, i3=0, i4=0, i5=1, i6=0, i7=0. What should be value of the select inputs s2, s1 and s0 for the value on the multiplexer’s output d to be 1?
s2=

s1=

s0

Answer 1

Answer: s2=1 s1=0 s0=1

Explanation:

Generally speaking, the multiplexer is a digital circuit , build with combinational logic, that acts like a switch, sending to the output the current value present at the input which order number (in decimal) is equal to the binary combination of the select inputs, expressed in decimal form.

If the multiplexer is 8x1, in order to be able to pass to the output any of the 8 inputs, the number of select inputs (n), must satisfy the following relationship:

M(number of inputs) = 2ⁿ

In this case, as the only input which present value  is "1" ,is the input i5, the value present at the input select must be the binary combination of s₀, s₁

and s₂, that yields the decimal 5, i.e.,  s₀ = 1  s₁ = 0  s₂ = 1.