I don't
know of any classic computer that came out with open source
DOS's (but a few open source monitors).
...so? None of my machines, classic or not, run the OS they came with
(if any); I'm here for the hardware, not the software, side of things.
To me, it doesn't matter if they were open-source back then, what matters
if whether I can get the source _now_. I have the source for the linux
distribution on this PC (Duh...). I have the LS-DOS source for my TRS-80
Model 4. I have most of the POS source for my PERQs (and I think there's
more on bitsavers I must look into sometime). Heck, I even have the
source listings for the 3 _calculators_ I use the most (HP41, HP71,
HP75).
-tony