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  • Re: PC/IX, was Don Norman: The Truth About Unix

    From John Levine@johnl@taugh.com to alt.folklore.computers on Tue Feb 3 02:29:15 2026
    From Newsgroup: alt.folklore.computers

    John Levine has posted before about a port of Unix to the 8086,
    that made use of the segmentation system to more or less protect
    the OS from errant user programs; the C compiler simply did not
    emit instructions to change the segmentation registers, so it
    worked pretty well as I understand it.

    As long is everything is limited to 64K data and 64K program.

    We ported System III Unix from the PDP-11. The 8086 code was slightly
    smaller than PDP-11 code, and the data formats were basically the same,
    so all the programs that worked on the PDP-11 worked on PC/IX. But we
    found rather quickly that people wanted bigger programs and that would
    have meant a major system redesign.

    Despite the lack of hardware protection PC/IX was very reliable and
    often stayed up for months at a time.
    --
    Regards,
    John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
    Please consider the environment before reading this e-mail. https://jl.ly
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