When I say 'just like a Unix', I mean: you log in and start up some terminal windows and it's sh and you can compile and run X11 software with configure scripts and gcc and you can print stuff with lpr and it all just works. It even runs Java --- my copy was completely self-hosting via Eclipse!
Years ago there was a single-floppy QNX demo disk: you booted from this and you got a basic desktop with dialup modem support and a web browser. SINGLE FLOPPY.
Hey, look! I was all set to write a paragraph about how sad it was that you couldn't get the bootable QNX CD any more, but look what I found!
http://www.qnx.com/download/feature.html?programid=19602
It doesn't even need registration and a login any more! Holy crap, I have to see if this still works...
Edit: looks like it won't install without a license key. I'll see if I can get one...
Edit: apparently I have an account with QNX dating back from 2012, with three hobbyist license keys, one of which makes the installation CD happy. I don't know whether these are still available, though.
Edit: so it installed into a VM in about two minutes flat, and I now have a very old copy of Firefox running. It can't see the network, but that's nothing to do with QNX and everything to do with my inability to set up kvm. I need to find a real machine to run this on.
Edit: it will only install from CD, not from USB (unetbootin doesn't help). And I've lost the power cable for my CD burner. So until I find it, I won't be able to proceed here. Sorry. Still good to know this still exists, though...