Earlier quoted context omitted.
The big issue with the done signal you're referring to is how do you generate it? In other words, how does the circuit "know" that it's finished execution? There are several options. One is to simply add a delay element to each circuit that is matched to the circuit's delay. Another is to use a circuit-level handshaking protocol, similar to that used in TCP. It's not an easy thing to tackle and leads to performance l…
I don't understand. It's clear to me when an adder is 'done'. Hm, so I'm guessing it does get more complicated than that. :)
Yes you're right, in the case of an adder it's pretty straightforward. It can get complicated in other circuits.