Enumeration Type: Enumeration type is used when it is represent values that are required for a specific operation. All values in an enumeration are user defined and cannot be any one from predefined types. These values may be character literals or named identifiers. For examples we can use values as ‘0’,’1’…..’a’,’b’,c’……..ADD, SUB, MUL……. Note here that we cannot use the numeric values such as 0, 1 etc VHDL will give error during synthesis, but we are to use them as character literals as ‘0’ , ‘1’ . Syntax: TYPE TYPE_NAME is (value{,value}); BIT Type: A bit type object can hold value ‘0’ or ‘1’. It is an enumerate type defined in the std library. The syntax of BIT type as defined in std library