A hardware description language used in electronic
design automation to describe digital and mixed-signal systems such as field-programmable gate
arrays and integrated circuits. Commonly known as VHDL it can also be used as a general purpose parallel programming language.
VHDL is commonly used to write text models that describe a logic circuit. Such a model is processed by a synthesis program, only
if it is part of the logic design. A simulation program is used to test the logic design using simulation
models to represent the logic circuits that interface to the design.