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.

What a fantastic talk! Thanks for sharing.

Perhaps a prior promise to someone else?

Somewhat related, there are people doing amazing things by modifying VHS players and tapping into the raw output from the tape heads (bypassing all of the player's other electronics), and then using modern signal processing techniques to extract unbelievable great footage from old tapes.

Check out this extraction/decoding of a 1987 VHS recording of The Cure:

https://www.youtube.com/watch?v=ks1wE_NXWv8

Play if full screen at whatever the highest resolution your screen can take advantage of, It's amazing! Check out the quality of the big headshots of Robert Smith, the resolution of stuff like his hair is way beyond what I believed VHS to be capable of - based on growing up recording similar music acts in the 70s and 80s.

Here's the software (and descriptions of the hardware and VHS player mods) they use:

https://github.com/oyvindln/vhs-decode

I suspect the recording technique/format on those is a similar analog signal on the tape - and from The Reg's article (quoting various sources) it sounds like they're already planning on similar approach:

"The software librarian at the CHM is the redoubtable Al Kossow of Bitsavers, who commented in the thread that he is on the case. On the TUHS mailing list, he explained how he plans to do it:

taping off the head read amplifier, using a multi-channel high speed analog to digital converter which dumps into 100-ish gigabytes of RAM, then an analysis program Len Shustek wrote: https://github.com/LenShustek/readtape

It is a '70s 1200ft 3M tape, likely 9 track, which has a pretty good chance of being recoverable."

I recently went through this. The problem is finding VCR's... there arent any.

And then the ones with manual tracking are even more rare, or out of the price range, which you likely need as the tracks degrade.

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.

Well, just replace micro-SD card with HDDs and it is pretty much how it works in the real life for absolutely massive data sizes.

Also, packing it up "taking forever" is irrelevant, that's latency, not bandwidth.

Dans Data (RIP that website, apparently) did this backup tapes to microSD cards update about 15 years ago.

He started with "Well, first we need to know how big our station wagon is. I hereby arbitrarily declare it to be a 1985 Volvo 240, which has 2.2 cubic metres of cargo capacity." and "I'm also going to assume that the wagon isn't really packed totally full of memory cards, such that they cascade into the front whenever you brake and will avalanche out of the tailgate when it's opened. Let's say they are packed almost to the roof of the car, but in cardboard boxes, which reduce the usable cargo capacity to a nice round two cubic metres."

The calculated "Assuming uniform and perfect stacking of objects of this volume, with zero air space, you can fit 24,242,424 of them into two cubic metres."

But he also addressed the packing problem, saying:

"In the real world there'd obviously be air spaces, even if you painstakingly stack the tiny cards in perfect layers. My size approximation, that ignores the more-than-0.5mm height of the thick end of the card, could make the perfect-layers calculation quite inaccurate. But if you're just shovelling cards into the boxes and not stacking them, though, there will be even more empty space between cards, and the thicker ends won't matter much.

To use a few words you may have to hit Wikipedia about - I know I did - a random close pack of monodisperse microSD-shaped objects will be considerably tighter than one for, say, spheres. I wouldn't be surprised if it only reduced the theoretical no-air-space density by 20%, provided you shake the boxes while you're filling them.

So let's stick with a 20% density reduction from random packing, giving 0.8 times the theoretical density of perfectly-packed cards. Or nineteen million, three hundred and ninety-three thousand, nine hundred and thirty-nine cards, in the boxes, in the station wagon."

He was writing in 2015, and settled on 16GB cards and being reasonable, getting 275 pebibytes. If we switched them to the 1TB cards mentioned upthread that'd be 17 exabytes in a 2 cubic meter stationwagon cargo area, or in a 67 cubic meter shipping container you'd get 575 exibytes. And that's the "load with a shovel and shack to pack down" number, so perhaps 720EiB if someone took that forever to carefully pack them.

Your 100 tons problem is real, it seems shipping containers (both 20 and 40 foot) seem to top out with a cargo payload of 28 tons. So let's call it "only" 161EiB shovel loads.

The font of all hallucinations and incompetent math tells me "The total amount of data on the internet is estimated to be around 40 zettabytes as of 2025, which is equivalent to 40,000 exabytes." So you'd only need 250 shipping containers or so to store a copy of the entire internet. And that's barely 1% of the capacity of a modern large cargo ship. I guess for reliability you'd use 500 shipping containers in redundant mirrored RAID1 config, each half travelling on a different ship.

Dan also noted: "Unfortunately, even if your cards and card readers could all manage 50 mebibytes per second of read and write speed, getting all of that data onto and off of the cards at each end of the wagon-trip in no more than 24 hours would require around 68,400 parallel copy operations, at each end."

That works out to 2.3 million readers for one parallel copy of one containers worth of data in one day. And 570 million for 250 container's worth.

https://web.archive.org/web/20250313181659/http://dansdata.c...

I managed about 1.5gb/s in 2007, between our solo and the office. With a server strapped to the back of a motorcycle.

https://flic.kr/p/4bQ8jz

> 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.

'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.

It’s so obvious in retrospect but I never considered they would do this! Thanks for sharing.

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!

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.

Of course I found it, AFTER I hit post...

https://retrocomputingforum.com/t/b-a-simple-interpreter-com...

Yeah I guess I still haven't wrapped my mind around that other part.

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.

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.

No "algorithm" shoving ads down your throat. Just a timeline of the accounts you follow with the posts in chronooogical order.

It shoves dark mode down your throat whether you want it or not. What could be cooler than that?

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...

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.