A priority encoder is a combinational circuit that implements a priority function. The operation of the priority encoder is such that if two or more inputs are equal to $1$ at the same time, the input having the highest priority takes precedence. The truth table for a four$-$input priority encoder is given below. With the use of X$\text{'}$s$,$ this condensed truth table with just five rows represents the same information as the usual $16-$row truth table.

$\backslash$table$[[$hputs$,$O utputs$],[D_3,D_2,D_1,D_0,A_1,A_0,V$