A bus is a set of signals which are grouped together conceptually (and often physically). One way to represent a bus is with std_logic_vector, which is somewhat similar to an array in software programming languages.

We can declare a 3-bit input bus called votes with

  votes : in std_logic_vector(2 downto 0)

With this declaration, you can use votes(0) to refer to bit 0 of votes, votes(1) for bit 1, and votes(2) for bit 2. The (2 downto 0) part specifies that this is a 3-bit bus where votes(2) is the MSB and votes(0) is the LSB.

Complete the architecture to build a majority encoder: the output y is 1 if the majority (i.e., at least two) of the input bits are 1, and 0 otherwise.

library IEEE; use IEEE.std_logic_1164.all; entity majority is port( votes : in std_logic_vector(2 downto 0); y : out std_logic ); end majority; architecture synth of majority is begin y <= '0'; -- A broken clock is right twice a day... end;

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Compiler/test output: