> Rather instructions were bit encoded in a single memory cell so some could be executed in parallel.

I think you might be remembering the later Seaforth/Greenarrays MISC (minimal instruction set computer) chips (they may have had some similar predecessors) that did that funny encoding. The RTX2010 was more like the Novix and had a 16 bit instruction word. See:

https://users.ece.cmu.edu/~koopman/stack_computers/sec4_5.ht...

That book has good coverage of the Forth chips of that era. This undergraduate thesis has some later developments:

http://fpgacpu.ca/stack/Second-Generation_Stack_Computer_Arc...

Related stuff from same site: http://fpgacpu.ca/stack