Describing circuits in text.
WHAT THEY ARE
Languages describing hardware structure and behaviour, from which circuits are synthesised.
WHAT THE TWO ESTABLISHED ONES ARE
One with a verbose, strongly typed style, common in Europe and aerospace One with a more concise style, dominant in commercial chip design
WHAT NEWER OPTIONS EXIST
An extended version of the second, adding verification features Languages embedded in general-purpose programming languages
WHAT THE CRITICAL DISTINCTION IS
Describing hardware, not writing a program.
WHY THAT MATTERS SO MUCH
Everything described happens simultaneously, not sequentially.
WHAT NEWCOMERS GET WRONG
Writing code that simulates correctly but cannot be synthesised into hardware.
WHAT SYNTHESISABLE MEANS
Describable as actual gates and storage elements.
WHAT IS NOT SYNTHESISABLE
Delays Unbounded loops File operations Much of what is useful in testbenches
WHAT A TESTBENCH IS
Code exercising a design in simulation, which need not be synthesisable.
WHAT TO SEPARATE STRICTLY
Synthesisable design from verification code.
WHAT TO LEARN FIRST
The subset that synthesises, and the standard patterns for state machines and registers.
