This paper explains how #Groq works. Like the boost indicated, the particularly fascinating bit is how network messaging is scheduled, not routed: with network of nodes known at compile-time, all time-synchronised and performing deterministic work, you can work out at which time slot each node will be free to receive the next message, so you can just fire and forget without having to worry about backpressure.
https://wow.groq.com/isca-2022-paper/
(and #ai, I guess )