Unix v4 Tape Found
(discuss.systems)454 points by greatquux 5 days ago
454 points by greatquux 5 days ago
> This is rare enough that I'm pushing the recovery
> of it up near the top of my project queue.
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:
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.
Someone in the Mastodon thread mentioned the Andrew Tannenbaum "Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway."
So I wondered about a modern day equivalent, looked up 1tb micro-sd cards (sold locally for Nintendo Switch) and calculated that there'd be roughly space for 400 exabytes of data in a shipping container filled to the brim with SD-cards.
(SDcard being 1tb for 1.092 x 1,499 x 0,102 CM's and a shipping container being 1203 x 235 x 239 CM's inside so holding 400 million SD cards)
Actually a shipping container full of micro-SD cards hurtling down the highway has lower overall bandwidth than a 56k modem.
That's because whoever's attempting to load an ideal 400 million micro-SD cards into one will take approximately forever carefully trying to line up even one row of them on the floor of a shipping container, before having the whole thing fall over like dominoes.
And even if they manage that, the whole thing will tumble over once they need to deal with the first row of the container's side corrugation. Nobody at the department of Spherical Cows in Vacuums thought to account for those dimensions[1] not lining up with the size of micro-SD cards.
If they do manage some approximation of this it'll take forever just to drive this down the road, let alone get the necessary permits to take the thing on the highway.
Turns out not a lot of semi truck trailers or roads are prepared to deal with a 40 ft container weighing around 100 metric tons (the weight of one packed to the brim with sand, a close approximation).
The good news is that such transportation gets more fuel efficient the longer the trip is.
The bad news is that the container will arrive mostly empty, as it's discovered that shipping container door panel gaps and road vibrations conspire to spread a steady stream of micro-SD cards behind you the entire way there.
Commuters in snowy areas held up behind the slowly moving "OVERSIZED LOAD!" with a mandatory police escort wonder if it's a trial for a new type of road salt that makes a pleasant crunchy sound as you drive over it.
Finally, an attempt to recover the remaining data fails. The sharding strategy chosen didn't account for failure due to road salt ingression into the container, cards at the bottom of the container being crushed to dust by the weight of those above, or that the leased container hadn't been thoroughly cleaned since last transporting, wait, what is that smell?
1. https://www.discovercontainers.com/wp-content/uploads/contai...
100 metric tons is nothing really when it comes to trucking, logging trucks in Sweden are commonly hurling through down dirt roads at 70-80km/h with 70 ton loads (mostly limited to that because that's the maximum allowed weight without oversize escorts currently), the Finns are experimenting with 100 ton loads for logging purposes (for environmental reasons).
That's not even mentioning Australian road trains that seem to commonly pull around 150 tons with some being up to 200 tons (The load would be slightly spread out to more containers but still one truck-load).
Still, 400 million SD-cards is still a silly experiment.
I tried setting that up, but now the trucker's union is refusing to talk to me, citing concerns that the platters will all spin up due to road vibration, derailing the truck in a ditch due to the cumulative gyroscopic forces.
They remain unconvinced that chatGPT has told me it "should be fine", and have inquired as to whether I don't have better things to do than trying to win increasingly obscure and contrived arguments on HN. Please advise.
Please let there be an ultimate force in the universe that spared this tape from tape degradation and/or magnetization that it can be read and extracted into a raw dump fs that we can preserve for all time. (fingers crossed)
Tapes from back then haven’t held up over the years. It all depends on the environment it was stored in.
There is one parity bit per 8 data bits, which is decently resilient - plus the recovery is pretty simple on the occasional bit flip. Combine that with the fact you can reference other sources to make up for missing/corrupted files - I think the chance that this is recoverable is pretty high provided the machine reading it is high quality. Checksumming on the source was unfortunately not commonplace until Unix 7, so it's unlikely there was any software-level integrity checks here. The tape looks like it was stored in a sealed container which is a very good sign. Those older tapes are actually more resilient than the later generation of tapes, and don't usually degrade the same way even with exposure to humidity.
I remember reading we're nearing a timeframe where VHS and cassette tapes made in the <=1980s will start degrading pretty seriously. So if you own lots of VHS or camcorder tapes you have a relatively short window to save old family videos... or just deal with fuzzy images and bad audio.
Very interesting storage format too - Those tapes actually held quite a bit of data (comparatively) - around 45MB (Although this one is shorter ~1000ft and probably carries about 10-15MB which is close to V4's source code, binary and documentation size).
> It is a '70s 1200ft 3M tape, likely 9 track, which has a pretty good chance of being recoverable.
Not old enough to have this kind of knowledge or confidence. I wonder if instead one day I'll be helping some future generation read old floppies, CDs, and IDE/ATA disks *slaps top of AT tower*.
You might be able to use that old floppy drive. But you won't be able to use that old Pentium machine the drive is in.
Because you will need several hundred gigabytes of RAM and a very fast IO bus.
The gold standard today for archiving magnetic media is to make a flux image.
The media is treated as if it were an analog recording and sampled at such a high rate that the smallest details are captured. Interpretation is done later, in software. The only antique electronics involved are often the tape or drive head, directly connected to a high speed digitizer.
And indeed that appears to be the plan Al Kossow has for the tape: https://www.tuhs.org/pipermail/tuhs/2025-November/032765.htm...
As for CDs, I don't see the rush; the ones that were properly made will likely outlast human civilization.
> As for CDs, I don't see the rush; the ones that were properly made will likely outlast human civilization.
Printed ones will last a lot more, but writable ones will degrade to unreadable state in a few years. I lost countless of them years ago, including the double backup of a project I worked on. Branded disks written and verified, properly stored, no sunlight, no objects or anything above them, no moisture or whatever. All gone just because of time. As I read other horror stories like mine, I just stopped using them altogether and never looked back.
>As for CDs, I don't see the rush; the ones that were properly made will likely outlast human civilization.
recordable CD-Rs or DVD-Rs do not last close to that long, and those are the ones that hold the only copies of certain bits (original versions of software, etc) that people are most interested in not losing.
manufactured CDs and DVDs hold commericial music and films that are for the most part not rare at all.
Yes, good distinction. Recordable media will most likely contain data an individual intended to save. But because it's recordable, the dyes and structures on the disc aren't as stable.
Long-lasting, good quality mastered optical media is probably mass produced and has many copies, including a distinct and potentially well-preserved source.
It's probably fair to say that a lot of mixtapes (mix CDs?) from the early 2000s are lost to dye issues...
'that were properly made' is doing a lot of work in that sentence. I've got a bunch of Sega Saturn and AKAI/Zero-G sample cds that are basically unreadable already due to disc rot. There was a lot of cheaply made optical media floating around in the late '90s.
and anything you "burnt" yourself has an even shorter life.
In many ways our storage media has become more ephemeral as capacities have increased - except LTO at least which seems to keep up with storage demands/price and durability, LTO is eternal (or long enough to be able to move it from LTO-(N-4) to LTO-N at least).
Just anecdata, but I had this concern when I worked in academia and we backed up all our data to writable DVDs. I was there 10 years after the start of the project and I periodically checked the old DVDs to make sure they weren't corrupted.
After 10 years, which was longer than the assumed shelf life of writable/rewritable DVDs at the time, I never found a single corrupt file on the disks. They were stored in ideal conditions though, in a case, in a closed climate controlled shelf, and rarely if ever removed or used.
Also, just because I think it's funny, the archive was over 4000 DVDs. (We had a redundant copies of the data compressed and uncompressed, I think it was like 3000 uncompressed 1k compressed) there was also an offsite redundant copy we put on portable IDE (and eventually SATA) drives.
Thank your procurement agent and hvac guy.
My team used to maintain go-kits for continuity of operations for a government org. We ran into a few scenarios where the dye on optical media would just go, and another where replacement foam for the pelican cases off gassed and reacted with the media!
I was the procurement guy for many years, and we had no HVAC guy - we were in a state university, and there was nothing special about the DVDs we bought, they were from Newegg and other retail places, we did buy the most expensive ones because our grants allowed us to, so maybe that's a factor.
I have no doubts (hence my anecdata statement) that there could be bad DVDs in there, or that maybe over a longer time horizon that the media would be cooked.
Wow! That's pretty interesting. I can imagine wanting to store optical media in Pelican cases or similar for shock protection, ability to padlock, etc. But yeah -- what's the interaction between whatever interior foam they chose and the CD-R media and dyes? Especially after 10+ years of continuous contact?
Optical media is probably best stored well-labeled and in metal or cardboard box on a shelf in a basement that few will rarely disturb.
It was a really fun project. We basically made these disaster kits, with small MFPs, tools, laptops, cell radios and INMARSAT terminals hooked to Cisco switches (this was circa 2002-3) and a little server. We had a deal that let us stow them in unusual places like highway rest stops.
We’d deploy them to help respond to floods or other disasters.
One of the techs cooked up a great idea — use Knoppix or something like it to let us use random computers if needed. Bandwidth was tight, but enough for terminal emulators and things like registration software that ran off the little server. So that’s where we got into the CD/DVD game. We had way more media problems than we expected!
Most of the CDs we burned at home in the 1998-2005 era were still good in recent years, some DVDs in there too. Luck, I guess. No delamination or rot. Really, my main problems were figuring out file types without extentions (burned on classic Mac OS) and... appropriate programs to open them (old Painter limited edition from 1998 needs... the same thing, pretty much).
OTOH, some 12 years ago I worked IT at a newspaper and we were moving offices. The archivist got an intern in a room in our section of the building and together they spent a month or two scanning, then committing whatever physical media to burned CDs (maybe DVDs) before chucking the former to the bin. Maybe a year after the move, a ticket was opened and I went to check the disks. None of them worked, CRC failures all over. I don't think they even considered testing them, or burning duplicates, or maybe they used a really bad drive which would produce media unreadable by anything else - although I'm only aware that this is a thing with floppies for example.
Cool tale! I have observed a mix of viable and unreadable user-burned CD media from the late 90s and early 2000s. It definitely depends on the quality of the media, quality of the burn/drive/laser, and how well it was stored interim.
My oldest disc is some bright blue Verbatim disk my childhood friend made for me so I could play our favorite game at home pre-2000. I have a bit-perfect copy, but the actual disc still reads fine in 2025 when I last tested it.
Yep, quality is definitely a factor here, as much as it can be. We had NSF funding pre-2008, so there was plenty of budget for quality media. We spared no expense, and while I stayed in a $60/night hostel in SF for conferences, our rewritable DVDs were the best money could buy at the time lol.
This seems to be how a lot of modern history is found.
I recently got to talk to a big-ish name in the Boston music scene, who republished one of his band's original 1985 demos after cleaning the signal up with AI. He told me that he found that tape in a bedroom drawer.
Will not be much different to the existing v5 source code, we can assume. https://minnie.tuhs.org/cgi-bin/utree.pl?file=V5/usr/source/...
I remember at one point I browsed tuhs.org in an attempt to find the source code for the original B (the language predating C) compiler. I don't think it should be in the 4th edition. I still wonder if there's a copy somewhere. I know there are a few modern implementations, but it would be interesting to look at the original.
The 'B' compiler was written in TMG-Compiler-Compiler. TMG (Transmogrifier)
https://github.com/amakukha/tmg
https://news.ycombinator.com/item?id=26722097
""Douglas McIlroy ported TMG to an early version of Unix. According to Ken Thompson, McIlroy wrote TMG in TMG on a piece of paper and "decided to give his piece of paper his piece of paper," hand-compiling assembly language that he entered and assembled on Thompson's Unix system running on PDP-7."
We are not worthy, friends. We are not worthy."
Tons of info, but not much source:
"The first B compiler was written by Ken Thompson in the TMG language around 1969. Thompson initially used the TMG compiler to create a version of B for the PDP-7 minicomputer, which generated threaded code. The B compiler was later rewritten in BCPL and cross-compiled on a GE 635 mainframe to produce object code, which was then re-written in B itself to create a self-hosting compiler. "
So... a B compiler would use GE 635/Multics as a OS.
Of course I found it, AFTER I hit post...
https://retrocomputingforum.com/t/b-a-simple-interpreter-com...
OT - Mastodon is seriously cool. If you haven't yet bothered, I suggest to everyone that you spend a bit of time exploring.
I was on Mastodon for three years. I deleted my account. When I found out that Charlie Kirk was murdered, my second thought was "well, best create yet another filter on Mastodon so I don't have to watch people celebrate Charlie Kirk being murdered" and when I caught myself having that thought I realised that being on Mastodon was a net negative for my wellbeing.
(I didn't like the guy either, by the way, or at least I knew enough about him that I knew I have much better things to do than listen to him. There are more than a few people like that, all of whom I wish find some peace in their hearts, and none of whom I wish to come to any harm.)
Mastodon is packed to the brim with literal psychopaths and people pretending to be psychopaths for imaginary Internet points. It is not an experience I suggest for anyone who is neither of those things.
I'm on mathstodon.xyz (mastodon for maths) and haven't seen any of that. So I guess it's the people you subscribe to.
But I have the freedom to decide what I want to consume.
> I'm on mathstodon.xyz (mastodon for maths) and haven't seen any of that. So I guess it's the people you subscribe to.
I was on an automotive-focused instance. I did see a lot of that.
> But I have the freedom to decide what I want to consume.
As do I; I had the freedom to delete my account, thus avoiding the need for any active measures to make my life free of schizoposting.
Yeah I guess I still haven't wrapped my mind around that other part.
Well, I won't debate whether "cool" is the right word. But ideologically I think federation is better than centralization when it can be made to work in practical terms, and Mastodon works.
It shoves dark mode down your throat whether you want it or not. What could be cooler than that?
This is amazing news for UNIX fans. Really hope the source can be recovered and put alongside the other historical UNIX source that's out there.
I really, really hope data can be recovered from this. I’ve read a bunch of the original sources, and such an ancient C would be especially interesting to study.
Very proud to have had this found at my University :-)
What are the odds that a medium like that has successfully stored the full data without error?
From the information I've read, quite likely, given that Utah is pretty dry. Also the original data might be stored in its uncompressed form, so even if there were some non-extensive damage it might still be possible to recover some data based upon guessing with context (if it contains text source code, otherwise if it is just the binaries then not that easy).
From 1973. See https://en.wikipedia.org/wiki/List_of_Unix_systems
Other posts on this subject, none with discussion:
https://news.ycombinator.com/item?id=45846438
I've added https://oldbytes.space/@bitsavers/115505135441862982 and https://www.theregister.com/2025/11/07/unix_fourth_edition_t... to the toptext as well. Thanks!
Also this post from Rob Pike with interesting thread of a bit more information about tape recovery https://www.tuhs.org/pipermail/tuhs/2025-November/032758.htm...
https://news.ycombinator.com/item?id=45857695 has discussion
It does now. :-) It didn't when I posted earlier
I wrote that article, but I no longer post my stories to HN because I am subject to a block and anything of my own I submit is flagged [dead]. I do not know why, and I have written to ask with no reply.
I only write 5-10 articles a week so I don't exactly spam the site at high frequency, and if I don't feel I can add more context or insight to a story, I don't write it -- except at the very slowest times of the year, and I wouldn't post those stories here.
Ah well.
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.