Consider a priority encoder given the truth table below Dete

Consider a priority encoder given the truth table below. Determine the order of priority for the priority encoder described by the truth table. Determine the Boolean expressions for Q_1 and Q_0 Write an ENTITY block that would describe this priority encoder.

Solution

(A)

Priority encoder is a type of encoder which sets priorities for every inputs.
Like in the above encoder, there are three inputs D1 , D2 , D3 and two outputs Q1, Q2

When value of D3 is 1, the both outputs have value 1 i.e. 3 in binary(irrespective of other inputs)
When value of D2 is 1, only output Q1 has value 1 i.e. 2 in binary(irrespective of other inputs)
When value of D1 is 1, only output Q2 has value 1 i.e. 1 in binary(irrespective of other inputs)
When value of D1, D2 , D3 is 0, both outputs have value 0 i.e. 0 in binary

it means that in the above encoder, priority can be ordered as

D3 > D2 > D1

(B)

Boolean expression for
Q0 = D3 + D2
Q1 = D1(~D2) + D3