Hardware description languages

Hardware description languages (HDLs) are languages that facilitate the conception, design, analysis/simulation, documentation, and manufacturing of digital computer systems. A digital system can be described at many different levels of detail: requirements, system, behavioral, and structural. Thus a system can be described from the system level to the logic gate level as a network of elements of varying degrees of complexity, including timing diagrams, behavior and structure. Fig. 1 shows examples of different descriptions of a 1-bit adder circuit. While a complete digital computer can be described at any level, the amount of low-level information would be too extensive for a human designer to comprehend, and higher-level languages are used to abstract or hide details, resulting in a system-level description of the design.