QModem ran on DOS, so the AT wasn't running UNIX. It's almost certainly being used as a terminal.
I can confirm that they did run Minix OK, although I remember the network support was iffy at best. We never got it to work at any rate. XENIX would have been hard to get your hands on. I think QNX would run on an AT as well, although my memory might be playing tricks on me there.
Re:QModem 4.51 Source Code
by EvanAnderson on Saturday May 03, 2025 @07:15PM
(#43883120)
Xenix definitely ran on a 286. I can't say re: Minix-- I never have used it (though I probably should just to have the experience). I believe there was a Crynwr SLIP packet driver.
I agree it's highly unlikely that the AT was running slirp. Wikipedia says an AT was a 286, so it wouldn't have been linux. Not even sure what the options would have been. Minix? Xenix?