Type of Data

The type of data flowing through the port must be specified to complete the interface
Data may be of many different types, depending on the package and library used
Some data types defined in the Standard package
- Bit, Bit_vector
- Boolean
- Integer, Real
- Time

PORT (input : IN BIT_VECTOR (3 DOWNTO 0) );

PORT (output, brdy, data : OUT BIT);