The bit_vector is a one-dimensional array type with elements being of type Bit. The bit_vector type is predefined in the Standard package.
type bit_vector is array (natural range <>) of bit;
The bit_vector type is an unconstrained vector. During the declaration the size of a vector is specified.
Assignments to a bit_vector can be done in the same way as in case of any arrays (using single element assignments, concatenation, aggregates, slices or any combination of the previous methods).
The bit_vector is an unresolved type and therefore any object of this type can have only one assignment in an architecture.
signal Bus : bit_vector(7 downto 0); Bus(0) <= '1'; Bus <= ('1', others => '0'); Bus <= Bus(6 downto 0) & Bus(7); Bus <= "01110010";
Bit, Standard Package