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Comment by lproven | Hacker News Reader

Anyway, since nobody much seems to realise this is quite a big deal, I will share the explainer I wrote yesterday:

https://www.theregister.com/2025/11/07/unix_fourth_edition_t...

Unix V4 is otherwise lost. It was the first version in C.

The bit in the article about the recovery procedure, which involves dumping info from the tape into '100-ish GB of RAM' and then using software to analyze it stuck out to me.

This video on the linked github page for the analysis software[1] is interesting:

https://www.youtube.com/watch?v=7YoolSAHR5w&t=4200s

[1] https://github.com/LenShustek/readtape

Well, the tape may not survive its second pass across the read head, so it's good to capture the analog waveform in as much fidelity as possible.

I wonder if they'll find it suitable to bake [0] the tape first, which is quite popular in the audio restoration world but I'm not sure how much it applies to computer tape.

[0] https://en.wikipedia.org/wiki/Sticky-shed_syndrome

I don't know much about tapes but it seems to apply, since the post mentions it:

> I'm hoping I don't have to bake it, since that takes a day

What a fantastic talk! Thanks for sharing.

    > This is rare enough that I'm pushing the recovery
    > of it up near the top of my project queue.

The reader is left to wonder what the software librarian at the Computer History Museum could have possibly found recently that warrants a placement ahead of Unix v4 in their project queue. A copy of Atlantian Unix from the ancient Library of Alexandria?

Perhaps a prior promise to someone else?

Or you know... just the definition of a FIFO Queue. I mean, using a FILO Stack to organize your work would certainly be a choice...

Definitionally if they're "pushing it near the top" they're not only using FIFO, there's a priority ordering involved...

My guess is there's stuff in progress and maybe they need to arrange access to or setup the readers for a tape that old and of potentially unknown format.

Yes it's probably better to finish in progress stuff first.

So much of this is old and potentially delicate and they don't have unlimited space to work in so they'd have to pack up some other in progress digitization project to setup the tape flux digitizer and maybe have to arrange to get the correct one for this type of tape too.

Interesting article. I agree it is kind of a big deal. Certainly worth the effort to try to restore

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