Hardware Description Language

In electronics, a hardware description language (HDL) is a specialized computer language used to describe the structure and behavior of electronic circuits, and most commonly, digital logic circuits.

A hardware description language enables a precise, formal description of an electronic circuit that allows for the automated analysis and simulation of an electronic circuit. It also allows for the synthesis of a HDL description into a netlist (a specification of physical electronic components and how they are connected together), which can then be placed and routed to produce the set of masks used to create an integrated circuit.

A hardware description language looks much like a programming language such as C; it is a textual description consisting of expressions, statements and control structures. One important difference between most programming languages and HDLs is that HDLs explicitly include the notion of time.

HDLs form an integral part of electronic design automation (EDA) systems, especially for complex circuits, such as application-specific integrated circuits, microprocessors, and programmable logic devices.

Due to the exploding complexity of digital electronic circuits since the 1970s (see Moore's law), circuit designers needed digital logic descriptions to be performed at a high level without being tied to a specific electronic technology, such as CMOS or BJT. HDLs were created to implement register-transfer level abstraction, a model of the data flow and timing of a circuit.

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