ADM-XRC SDK 2.8.1 User Guide (Linux)
© Copyright 2001-2009 Alpha Data
subtype byte_t is std_logic_vector(7 downto 0);
A byte_t holds a single byte value.
The type byte_t is used to construct the byte_vector_t type. Since it is a subtype of std_logic_vector, many standard VHDL functions can be used to manipulate values of this type.