> I would guess that less than 20% of the core SYSTEM is essentially the same (but often quite a bit enhanced). For the rest of the software, I would think it's even less.

ZWEI, TV and SI makes up the majority of the base system which is far more than "20%" percent, which is ignoring EH, WINDOW, and anything else that is essentially processor agnostic.

The target processor is not that important from the users point of view, to the point that Lambda and CADR shared the exact same source code, and microcode. The Explorer I was essentially a Lambda. Much was "feature" protected with #+/#- to the point where many of the systems worked on Genera as well.

So that seems at par with the CPU architectures that Symbolics made, which is "just" a change to the compiler .. and not the overall system .. which is what was being discussed. But yes, Symbolics did design hardware done by Symbolics and made sure it worked on their system .. not sure what your point is other than giving an incorrect view of history and what Symbolics actually did to the Lisp Machine system parts (Symbolics work was much more interesting when it came to other systems like the 3D stuff and what not).