Different Type of Hardware

Topics: Electronic design automation, VHDL, Verilog Pages: 10 (3614 words) Published: May 24, 2013
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 particular VLSI became more popular. Separate work circa 1979 at University of Kaiserslautern produced a language called KARL, which included design calculus language features supporting VLSI chip floor planning and structured hardware design. The same work was also the basis of KARL's interactive graphic sister language ABL, implemented in the early 1980s as the ABLED graphic VLSI design editor, by the telecommunication research center CSELT at Torino, Italy. In the mid 1980s, a VLSI design framework was implemented around KARL and ABL by an international consortium funded by the commission of the European Union . By the late 1970s, design using programmable logic device (PLD)'s became popular, although these designs were primarily limited to design finite state machines. The work at Data General in 1980 used these same devices to design a then modern system, the Data General Eclipse MV/8000, and commercial need began to grow for a language that could map to well to them. By 1983 Data-I/O introduced ABEL, to fill that need. As design shifted to VLSI, the first modern HDL is  Verilog was introduced by Gateway Design Automation in 1985. Cadence Design Systems later acquired the rights to Verilog-XL, the HDL-simulator that would become the de facto standard (of Verilog simulators) for the next decade. In 1987, a request from the U.S. Department of Defense led to the development of VHDL (VHSIC Hardware Description Language, where VHSIC is Very High Speed Integrated Circuit). VHDL was based on the Ada programming language, as well as the experiences that had been learned with the development of ISPS earlier. Initially, Verilog and VHDL were used to document and simulate circuit designs already captured and described in another form (such as schematic files). HDL simulation enabled engineers to work at a higher level of abstraction than simulation at the schematic level, and thus increased design capacity from hundreds of transistors to thousands....
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