VHDL (VHSIC Hardware Description Language) is a hardware description language used in electronic design automation to describe digital and mixed-signal systems such as field-programmable gate arrays and integrated circuits. VHDL is also used as a general purpose parallel programming language. VHDL was originally developed at the behest of the United States Department of Defense in order to document the behavior of the ASICs that supplier companies were including in equipment. The idea of being able to simulate the ASICs from the information in this documentation was so obviously attractive those logic simulators were developed that could read the VHDL files. The next step was the development of logic synthesis tools that read the VHDL, and output a definition of the physical implementation of the circuit. Due to the Department of Defense requiring as much of the syntax as possible to be based on Ada, in order to avoid re-inventing concepts that had already been thoroughly tested in the development of Ada, VHDL borrows heavily from the Ada programming language in both concepts and syntax.
We have developed tutorials on the philosophy that the beginning student need not understand the details of VHDL -- instead, they should be able to modify examples to build the desired basic circuits. Thus, they learn the importance of HDL-based digital design, without having to learn the complexities of HDLs. Those complexities can be reserved for a second, more advanced course.