Not totally sure - I think the modern versions come from signetics, but I'm not really a chip-head.
I do think the article nick refers to is interesting, but to my mind, no matter how much or little space one has, *style* is most important, be it machine code or high-level language.
I think that of course was best expressed by Ken and Dennis having to start Unix on a PDP-7 after coming from Multics. There was still plenty of machine code specific to the DEC machines, which of course got quickly replaced by high-level bcpl leading to C. Heh, but then to prove the portability of not relying solely on machine code, putting Version 6 on the Interdata 8/32. (proven near simultaneously by the Wollongong uni with the smaller 7/32 and blowing Ken's mind).
50 years ago, flipping bits manually or with assembler, and with very limited resources, style might have been elegant or confused with obfuscation.
The real genious is having a LOT of resources available, yet still using them wisely. Like TC / Dcore / Picore does. To me it's not just a matter of being small for small's sake, but having a style, or raison d'etre that keeps me hooked on *core.