Monday, December 10, 2007

Xenix - a blast from the past - Looking back at Microsoft UNIX

Xenix was Microsoft's version of UNIX, licensed from AT&T back in the late 70s, then later acquired by the Santa Cruz Operation (SCO) and distributed as SCO UNIX. Microsoft did not sell Xenix directly to end-users, but instead licensed it to OEMs.

Xenix was originally based AT&T UNIX System III, but also incorporated elements from BSD. Version 2.0 was based on UNIX System V, and later ported to 32bit / i386, and also introduced TCP/IP and SCSI support.

Trusted Information systems also developed a Trusted Xenix variant, using the Bell-LaPadula model of multilevel security and achieved a NSA B2 rating (TCSEC) - the second highest rating ever achieved by an evaluated operating system.

Overall, it was a pretty complete UNIX system (later versions got as large as 96 5.25" floppy disks) and came with The X Window System, ed, vi, sh, csh, vsh, uucp, terminfo, mapchan and so on.

Good news is, you can run it yourself. There's at least 3 ways to run Xenix:

I. i386 Xenix

  1. Track down a 386 version... my floppies are all dead X-D
  2. Install using qemu
II. Tandy Xenix
  1. Get the Xenix floppy images from - This is a complete Xenix install for the Tandy 6000 series.
  2. Get a Tandy 6000 or write an emulator (none exists from what I've seen).
III. Apple LISA Xenix!
  1. Get a copy of Xenix for LISA: - it took me a while to track this one down.
  2. Get a LISA Emulator: - LisaEM is an Open Source multiplatform LISA Emulator.
  3. Enjoy!

Here's some Xenix documentation to get you started:


Anonymous said...

Thanks for that. I really enjoy messing around with old OS's, and I'd been wanting to try Xenix.

Anonymous said...

The new lisa emulator (idle) can actually run Xenix..

You'll just have to use lisafsh-tool from lisaem to convert the DART diskette images to DC42 (disk copy 4.2), and it will install just fine.. However Xenix on a 5mb hard disk is... very tight.. Hopefully either lisaem will update its profile emulation to work, or idle will allow additional disks...

Anonymous said...

From what I know, there was NO x-server for Xenix. At least, no one developed by SCO/microsoft themselves. And no version with 96 disks either.

Maybe you're confusing it with SCO Unix, the Xenix successor

cmihai said...

Yeah, it was from SCO, not Microsoft. It think it was SCO UNIX or ODT, but it was pretty much Xenix.

It had a fully blown X environment, so it probably was ODT. I'll see if I can find traces of the stuff at my old place, heh.

Andre said...

I have downloaded some disk images (i386) from an abandonware site. Trying to boot them in VirtualBox is no success. The boot screen appears but stops with an I/O error while reading the from the floppy drive. (I mounted the floppy image in VirtualBox) I suspect a timing problem with the emulated floppy drive.