Saying "share the internet connection" is quite a stretch though if you just had a terminal connection to some other host which then connected to the internet. I'd associate "sharing a connection" with some (perhaps NATed) IP routing. And they mention NAT, thus my question.

Based on their mention of "coax" I bet they have a Linux box w/ a modem doing dial-up PPP to an ISP, and a 10Base-2 NIC that they used to attach another PC. The Linux box was doing IP masquerading (NAT) to share the PPP connection w/ the machine(s) on the 10Base-2 LAN.

Having the IBM AT a a serial terminal would let somebody run CLI-based software on the Linux box (like Lynx, an IRC client, FTP, etc). You'd just be using a shell account on the Linux box.

I did stuff like this in the early 90s at home and later at a company I worked at (sharing a single dial-up connection over 10Base-2 with 5-ish Windows 95 PCs).

Maybe your association would be different / the terminology would make more sense if you were online in the early 90s?

BUT, it was definitely possible to do what you're describing with some combination of a dialup shell account, a terminal program like qmodem and something like https://en.wikipedia.org/wiki/Slirp

I think running SLiRP on the Linux box and a SLIP client on the IBM AT was probably a stretch, but it's certainly possible. At that point it probably would have made more sense to grab an NE2000 NIC and throw the IBM AT onto the coax network.

Most network software for DOS was LAN-oriented, like Novell or NetBIOS. Just drive mapping and printer redirection. I'm not aware of a TCP/IP connectivity suite being available for DOS in that era, and I'm not sure how it would have worked given that DOS provided no networking libraries to hook into.

Oh I wasn't trying to reverse-engineer his network from that comment, just saying that this was a thing that was possible and that people did at the time.

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?

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.

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 was online in the 90s and I did have a 286 PC. Thus my questions. (That PC was running DOS and didn't have much of a chance to have IP connectivity.)