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In electronics, a hardware description language (HDL) is a specialized computer language used to program the structure, design and operation 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, simulation, and simulated testing of an electronic circuit. It also allows for the compilation of an HDL program into a lower level specification of physical electronic components, such as 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 microprocessors. ==Motivation== 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. There are two major hardware description languages: VHDL and Verilog. There are different types of description in them "dataflow, behavioral and structural". Example of dataflow of hdl: library iEEE; use iEEE.STD_LOGIC_1164.ALL; use iEEE.STD_NUMERIC_STD.ALL; entity not1 is port(a:in STD_LOGIC; b:out STD_logic); end not1; architecture behavioral of not1 is begin b <= not a; end behavioral; 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hardware description language」の詳細全文を読む スポンサード リンク
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