1. 13

  2. 10

    I have not forgotten Xenix, nor cross-compiling C/C++ between it and 32-bit extended DOS. One does not simply walk into Mordor…

    1. 6

      FTFA: “Even though it came first, Unix was probably more powerful than MS-DOS.”


      1. 4

        The article itself is quite poor - a lot of it seems to be a simple rewrite of the Wikipedia article.

      2. 1

        Here’s a much better link someone posted on HN version with tons of detail:


        My response reposted below.

        That’s awesome! Thanks for the link as it fills the big picture in nicely for me. Should be the original article given level of detail. Trips me out that NT was developed on OS/2 with mail servers running Xenix. Combined with other articles, I actually see Microsoft playing it smarter than I thought drawing from all the best tech families:

        1. Create a better UNIX than UNIX. UNIX microcomputer market forms as a side-effect due to marketing.

        2. Move UNIX features into CP/M in MS-DOS.

        3. Clone OpenVMS architecture with enhancements and emulators for older OS’s.

        4. Develop on OS/2 for better reliability, pace, and inspiration. I’m sure OS/2 stuff ended up in NT past the emulator. I’d be interested in a link that went into that in detail. (I know IBM & MS originally worked on OS/2 together but I mean specific features of OS/2 in NT.)

        5. Run mail and gateways on Xenix as UNIX was great at that sort of thing.

        6. Run whole business on a single AS/400 that just gets shit done mainframe-style.

        7. Replace all of the above with one product that has key attributes of all of them in usable package on cheaper hardware.

        They don’t look as dumb now as I thought when I was younger comparing MS-DOS to BSD’s or Linux. ;)

        re Linux

        The author asserts multiple times that Linux comes from Xenix somehow but didn’t seem to prove it. Says the architecture, standard, and microcomputer UNIX was first done by Xenix. Then Linux did one. Past that, nothing. Is there some resource with specific evidence that Linus got Linux design aspects from Xenix as opposed to another UNIX? And my original sources said he started with Minix changing stuff in his design that didn’t suit his hardware or needs. So that needs to be factored in.

        re secure UNIX

        One thing INFOSEC people might find interesting about Xenix is the re-implementation done by Trusted Information Systems: Trusted Xenix. It was the first, certified, security-oriented UNIX that had a combo of features for extra security plus backward compatibility with Xenix apps. These included trusted path, mandatory controls, integrity controls to limit viral damage, some suppression of covert channels, and especially their solution to setuid problem. That they published a solution while mainstream UNIX just kept the problem around was an early illustration of a recurring problem in mainstream INFOSEC where prior, proven solutions get ignored.

        Here’s the evaluation report with all of its security features and such for anyone interested in learning about it. Or comparing it to security of modern UNIX’s:


        Particularly interesting to compare it to SELinux, FreeBSD w/ SEBSD, or OpenBSD.

        1. 1

          My only real encounter with Xenix was in the late 1980s, when a school friend’s brother had it running on their 386/33 (this was at a time when all of us had 8088/80286 machines), dual booting with MS-DOS. He showed it to us a few times and it was horribly confusing - I don’t think I even understood what an operating system was back in those days.