Part 0 answers: What is a protocol, really?

Before any signal names, a protocol is an agreement between two pieces of hardware that cannot see inside each other. Each side can only observe the wires, so everything it relies on has to be promised by the other side and checkable on those wires.

This part builds the vocabulary the rest of the course uses: roles, the three layers of every spec (signals, meaning, timing), protocols as pairs of state machines, topologies, layering, and the three models of communication (memory, message, stream).

After this part you can

• Explain what a spec promises beyond its port list.

• Read and draw a timing diagram without guessing.

• Say which layer of a stack should own a guarantee, using the end-to-end argument.

Lessons

Every lesson in this part is ready. Work through them in order: each one sets up the problem the next one solves.

Related topics

• Course hub

• Next: Part 1 · Timing and Clocking