UNIX V4 tape successfully recovered: First ever version of UNIX written in C is running again

Lounge Linux lounge
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Computer History Museum software curator Al Kossow has successfully retrieved the contents of the over-half-a-century old tape found at the University of Utah last month.

UNIX V4, the first ever version of the UNIX operating system in which the kernel was written in the then-new C programming language, has been successfully recovered from a 1970s nine-track tape drive. You can download it from the Internet Archive, and run it in SimH. On Mastodon, “Flexion” posted a screenshot of it running under SGI IRIX.

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Source: https://oldbytes.space/@flexion/115752573933914452

[1] https://www.theregister.com/2025/12/23/unix_v4_tape_successfully_recovered/

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Yeah it’s nice that history is found and saved, so much history is lost to time :sad_but_relieved_face:

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Esp digital history :frowning:

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That looks great. Way beyond it’s time. Even the terminal looks great with the transparency.

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That’s quite an achievement considering how the media must have degraded over the years.

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I question if something from 1970 would have a button labeled ‘Internet’ (Gore hadn’t invented it yet rofl!) or even the idea of transparency, frankly it probably didn’t include a GUI at all (but I don’t know).
All that stuff is the host running it (more modern OS), right ?

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The internet was invented in the late 1960s. The web, which is just part of the Internet wasn’t invented until the 1980s. If you want a really good book about it, try “Where Wizards Stay Up Late”

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It depends on your definition of the ‘Internet’, I would say much later. Though the roots of it were early, including the DARPA-net.

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I define it as when the first connection between distinct networks was made.

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And I define it as when it was significant enough for someone (a business, an individual, etc) to want to have a presence there, vs just a collection of nodes connected by a cable.

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In think the contents in the window with the title aterm is Unix 4.

Not sure what the rest is.

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it would be great if there were some instructions on how to get this running in a vm with simh.

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I believe there is info about that at [1], where it says:

Fortunately, Angelo Papenhoff offers a processed version, complete with a README telling you how to run it. For further guidance, then on Reddit, drop_table_allusers suggests:

In the directory where you downloaded all the Unix v4 files, start SimH pdp-11 executable and pass the boot.ini found in the Unix v4 files as parameter. Then press ‘k’, type ‘unix’, press enter and it boots…

[1] https://www.theregister.com/2025/12/23/unix_v4_tape_successfully_recovered/

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Thank you for pointing that out