hi,
you can first specify a new array type using this syntax:
TYPE type_name IS ARRAY (specification) OF data_type;
then you can make use of the new array by this code:
SIGNAL signal_name: type_name [:= initial_value];
EXAMPLE for saving 6 bytes:===============================
TYPE matrix IS ARRAY (0 TO 5) OF STD_LOGIC_VECTOR(7 DOWNTO 0); --type definitions
SIGNAL x: matrix; --signal declarations
matrix <= ("00010101","11111111","10101010","00000000","11001100","11100010"); --an example of signal assignment
Hope this helps;