What is the oldest UNIX(-like) system that can be legally downloaded and run in a VM or emulator on a modern PC running Linux?

  • 6
    Maybe a good place to start is a PDP-11 emulator running Unix V6 pdp11.aiju.de Commented Jul 31, 2022 at 22:25
  • 4
    Also see here where it appears they have set up Unix v5. (I've not tried it. But I intend on trying it out.) They are running a version which suggests access at least to a binary. I'm assuming it's a legal one. But I don't know.
    – jonk
    Commented Jul 31, 2022 at 23:00
  • 2
    Likely everything before standalone release of BSD has license and copyright issues, so likely candidate might be BSD Net/1.
    – Justme
    Commented Aug 1, 2022 at 1:38
  • 6
    @Justme Caldera granted a license for “ancient” versions of UNIX, see this document for details. The versions covered are V1-7 on the PDP-11 and 32V. Commented Aug 1, 2022 at 8:30

1 Answer 1


Unix V1 kernel with Unix V2 userland runs on SimH. Can't get much older than that. See the project page for details.

This page has a list with more old versions you can run. Unix V6 is much less hassle.

  • 4
    @Someone if you read the "ancient" page itself, you can find the statement "The kernel was modified to recognize the 0407 executables from V2, because the V1 userland seems still to be lost"
    – Tommylee2k
    Commented Aug 3, 2022 at 6:03
  • 4
    PDP-7 Unix is older and is available (for some value of available). Commented Aug 6, 2022 at 5:51

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