Hardware Description Languages (HDLs)
HDLs are like languages for talking to computers about how to build electronic circuits. Two popular HDLs are VHDL and Verilog. Before HDLs, people used pictures to design circuits, but they needed a text-based way to do it.
Verilog is one of these languages, and it’s used to describe how digital systems work. It’s quite flexible and can describe everything from small circuits to complex computer parts. It was first created by a company called Gateway Design Automation in the 1980s. Later, it became an industry standard, and organizations like Open Verilog International (OVI) helped make it open and standardized. Many people find Verilog easier to learn because it’s similar to the C programming language.
HDLs can describe digital systems in different ways: behavior, data flow, and structure. For example, you can describe a simple thing like adding numbers without saying how it’s done or giving all the details. This flexibility makes it useful for different stages of design. HDLs are great for a “top-down” approach, where you start with the big picture and work your way down to the details. You can test your design at a high level and then refine it until it matches the actual hardware.
VHDL vs. Verilog
VHDL is another HDL that’s based on the ADA programming language. People use either VHDL or Verilog, and both can do most things in digital design. Some say Verilog is better for making actual hardware, while VHDL is better for simulating big systems. The choice often depends on what people are used to.
System Design Languages
Besides VHDL and Verilog, there are other languages like System C for describing big systems. These languages help different teams work together when designing large systems. They also help find problems early, making the design process faster. So, HDLs are like languages for designing electronics, and Verilog is one of them, known for its flexibility and similarity to C. They’re essential for building everything from small circuits to complex systems, and they make the design process more efficient.
What are the two popular hardware description languages (HDLs) commonly used in digital system design?
The two popular HDLs are VHDL and Verilog.
Why was there a need for text-based HDLs like VHDL and Verilog in digital circuit design?
Text-based HDLs were introduced to provide a textual method of documenting circuits and feeding them into simulators, as opposed to graphical schematics. This allowed for a more versatile and standardized way of describing digital circuits.
Who developed Verilog, and how did it evolve from a proprietary language to an open standard?
Verilog was initially developed as a proprietary language by a company called Gateway Design Automation around 1984. In 1990, Cadence acquired Gateway Design Automation and eventually opened up Verilog to prevent the industry from shifting to VHDL. Open Verilog International (OVI) was formed to create a vendor-independent language specification, and it led to the creation of IEEE standards for Verilog.
What are the different levels at which HDLs can describe a digital system?
HDLs can describe a digital system at several levels, including behavioral, data flow, and structural levels. Behavioral describes the function, data flow provides logic equations, and structural specifies gates and interconnections.
What is the advantage of using HDLs in a top-down design methodology?
HDLs support a top-down design methodology, starting with a high-level description and gradually refining it. They are technology-independent, meaning a design described in HDL for current technology can serve as a starting point for future technology implementations.
What are the syntactic roots of Verilog and VHDL?
Verilog has syntactic roots in C, making it easier for those familiar with C. VHDL has roots in ADA and is known for supporting the design and documentation of large systems. Both languages have approximately equal global market share, with Verilog being favored for synthesis and VHDL for simulation of large systems.
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