VHDL
/vee-aych-dee-ell/ · noun · Development · Origin: 1987
Definitions
VHSIC Hardware Description Language, used to describe and simulate digital electronic systems at various levels of abstraction. VHDL is one of two dominant languages (alongside Verilog) for programming FPGAs and designing ASICs, where the 'code' doesn't run sequentially but describes physical circuits that operate in parallel.
In plain English: A language for designing computer chips and electronic circuits, where the code describes physical hardware rather than software instructions.
Example: Writing VHDL isn't really programming — you're describing circuits, and every signal assignment happens simultaneously, not one after another.
Origin Story
The Pentagon's hardware description language with a recursive acronym
The U.S. Department of Defense commissioned VHDL in 1983 to document the behavior of the ASICs in military equipment. The name stands for **VHSIC Hardware Description Language**, where VHSIC itself stands for **Very High Speed Integrated Circuit** -- making VHDL a nested acronym.
VHDL was designed to describe hardware, not software. It specifies how digital circuits behave and are structured. Every signal has a type, every process has a sensitivity list, and concurrent statements model parallel hardware execution naturally.
Initially just for documentation, VHDL soon gained synthesis capabilities -- tools that could automatically generate actual chip layouts from VHDL code. Today, VHDL and its rival Verilog are used to design everything from FPGAs to the processors in your phone.
Coined by: U.S. Department of Defense (IBM, Texas Instruments, Intermetrics)
Context: U.S. DoD VHSIC program, 1983
Fun fact: VHDL's syntax was based on Ada (another DoD-commissioned language). Hardware engineers who learn VHDL often find software programming confusing because they've been trained to think in parallel execution rather than sequential.