Alternatives to the WAM

Question

I remember once reading that there were at least two other alternatives invented roughly at the same time as the WAM. Any pointers?

Answer 1

In the technical note entitled An abstract Prolog instruction set, Warren also references another compiler by Bowen, Byrd, and Clocksin. However, he says that the two architectures have much in common, so I don't know whether that compiler could be really considered as an alternative.