Different Type of Hardware
A hardware description language(HDL) is a language from a class of computer languages, specification languages, or modeling languages for formal description and design of electronic circuits, and most-commonly, digital logic. It can describe the circuit's operation, it’s design and organization, to verify its operation by simulation. The 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 other programming languages and HDLs is that HDLs explicitly include the notion of time. HDLs form an integral part of Electronic design automation systems, especially for complex circuits, such as microprocessors. First of all we must know the history of the HDLs before we know the different and types of HDLs. The first hardware description languages appeared late of 1960s is looked like more to traditional languages. In 1971, C. Gordon Bell and Allen Newell's in their text Computer Structures described that lasting effect. It was the text where the concept of RTL was introduced in the ISP language to describe the behavior of the DEC PDP-8. The language became more broad spread with the introduction of Digital Equipment Corporation (DEC) PDP-16 RT-Level Modules and a book describing their use. At least two implementations of the basic ISP language (ISPL and ISPS) followed. ISPS was well suited to describe relations between the inputs and the outputs of the design and quickly became adopted by commercial teams at DEC, as well as a number of research teams both in the USA and in NATO allies. However, the ability to synthesize logic turned out to be limited, as the simulator output assumed that the design would be reduced to practice using those same DEC RTM style PDP-16 modules. The RTM's product never really took off commercially and DEC stopped marketing them in the mid-1980s, as new techniques and in