Comment by retrac

Robert Nordier's port of v7 to x86 probably didn't get the attention it deserves.

It's what it sounds like: v7 Unix ported to x86. Unix v7 was portable enough and the PDP-11 architecturally similar enough to x86 that almost all the code works without change. (Many of the changes from v6 to v7 were to make Unix more portable; it was already running on at least 4 different architectures by 1980.)

I wonder if the obscurity is because the x86 v7 source was an archive inside an archive? Seems a minor thing but not having it to browse online is likely to be an off-ramp for most.

https://www.nordier.com/v7x86/v7x86-0.8a-all.tar.xz has releases/v7x86-0.8a.tar.bz2 (you'll want to use a -C prefix it explodes in the current directory). Source is in usr/sys and usr/src like normal for v7 Unix.

And yes, your modern Linux system's GNU tar is reading the ancient v7 tar format just fine. Neat, eh?

You might find the modern "file" command can still recognize the v7 a.out binary format too:

    $ file usr/bin/compress  
    usr/bin/compress: a.out little-endian 32-bit executable not stripped

Unix version 7 remains a sort of lowest common denominator almost half a century later.