[rst]

Some of this needs checking -- you could not run Unix on Symbolics hardware. LMI did have machines that ran both OSes -- but Unix was running on a separate 68000 processor; see, e.g. http://www.bitsavers.org/pdf/lmi/LMI_lambdaOverview_1982.pdf

(3600-series Symbolics machines also had a 68k "front end processor", but no Unix port was provided for it; they also ultimately had a C compiler that could generate code for the "Lisp processor", but the code it generated was intended to run in the Lisp environment.)

It's also worth noting that systems-level code for Symbolics machines (and, I presume, LMI as well) made frequent use of "unsafe subprimitives", misuse of which could easily crash the machine. And, unfortunately, if you needed to, say, get anything close to hardware bandwidth out of the disk drives, some of this became well-nigh unavoidable, due to poor performance of the OS-level file system (LMFS).

[lispm]

What one could do was running hardware Lisp Machines from Symbolics on VME boards inside a SUN: the UX400 and UX1200.

Later Open Genera was sold as a Virtual Lisp Machine running on a DEC Alpha / UNIX system.

[skissane]

Apparently Open Genera now even runs under macOS on Apple M1s: https://twitter.com/gmpalter/status/1359360886415233029

I think the big problem with Genera is the licensing. Although it comes with source code, it is proprietary software, and buying a license is expensive. I think the owners of the Symbolics IP have prioritised squeezing the maximum revenue out of a declining user base over trying to grow that user base.

I'm surprised "Open Source LispOS" projects have largely failed to gain traction. Writing your own OS is (at least in some ways) easier than it used to be (especially if you target virtualisation rather than bare metal). There seem to be a lot more people saying "LispOS is what we need!" than actually writing one or contributing to an existing effort to write one.