The 'no apps' perspective: https://www.mail-archive.com/fonc@vpri.org/msg04503.html, found via https://twitter.com/yoshikischmitz/status/1202581577571557381

I didn't know about FONC - is there a current one? This one suddenly stopped by the looks of it

I’ve never seen an example of a “lisp machine”. Can you also describe those as being “without apps” and an “operating system”? It sounds like they might.

<https://www.ifis.uni-luebeck.de/~moeller/symbolics-info/genera/genera.html> has some info about the Symbolics lisp machine.

The key to Genera's intelligence is the sharing of knowledge and information among all activities. At any time, the collection of all the state of all the processes is called the environment (Figure 4). Any function running in any process can use any piece of data in the environment directly. You do not need laborious special-purpose protocols or intermediate files.

So it sounds like it also has no 'apps'? Diagram:

I'm not sure what to make of "no operating system" claims. Back in the day there was a more liberal definition of "operating system". At one point, a working informal definition of OS was whatever software was loaded into memory at boot. Nowadays, it seems that "operating system" is synonymous with "Unix", so if an OS doesn't have the same architecture and layering as Unix, then it isn't an OS. I could be mischevious, and claim that Unix is an image based software environment written from the ground up in C. There's no OS, because it is C all the way down, right?

I think folks say no OS because OS now mostly means Unix architecture like you say.

yeah I'm on that one too