As the complexity of Very Large Scale Integrated(VLSI) circuits increased over the past decades, it became more and more crucial to find ways to improve the development process, including the ability to verify the design. This led to the development of hardware description languages (HDLs), of which today VHDL and Verilog are the two most commonly used ones.
The main purpose of HDLs is to allow a developer to easily describe hardware circuits of the type that would be integrated into ASICs or used to program FPGAs with. In addition, these HDLs also make it possible to simulate the design and to validate its functional correctness.
In this chapter, we will look at an example that uses VHDL for the side of the programming that is implemented on the FPGA. VHSIC Hardware Description Language (VHDL) as a language first appeared in 1983, when it was developed by the US Department of Defense. It was intended to act as a way to document the behavior of ASICs that suppliers...