Floppy disks are rapidly aging, and archivists are working hard to preserve what data is left. This has led to the development of advanced floppy controllers capable of capturing the raw flux data from disks. [bzotto] was experimenting with the Applesauce archival hardware, and had some fun with the tools.
The result is a highly esoteric Easter egg. [bzotto]’s Picturedsk tool takes a bitmap image as input, and imprints that image into the magnetic flux of the disk. Thus, when viewing a dump of the disk’s magnetic flux on an archival program, the hidden image will be revealed. As an extra treat, it also writes a 1-bit version of the image to track 0, along with a barebones Apple ][ program to display the image and implore the user to investigate further.
It’s a fun hack that we could imagine being used as part of a game at a retro computing con, when we get to go back to those of course. We’ve seen Applesauce used before, too. If you’ve got your own archival projects on the go, be sure to let us know!
I like this magnetic analog of a DiscT@2.
That kind of ideas is what I liked about old computing and programs in general. Nice vibe, that got missing as everything got very professional and “clean”.
Totally useless and totally cool! (Actually you could use it for steganography I suppose, if anyone used disks anymore.)
I had a look recently into some “flux readers” and despite what I originally thought, they are NOT raw flux readers, but are logic analysers connected to the already decoded magnetic domains on the disk, with very high precision on recording the timing of the pulses.
I was a little disappointed, as I expected from the wording (both here and on many of the sites advertising such readers) that “raw” would mean an analog read of the magnetic strength and polarity of the magnetism on the disk (as you would get looking at a digitised analog cassette tape).
In that way you could (with appropriate decoding software) decode disks that had been heat affected or been stored too close to a magnet (without complete erasure) and had bits too weak to trigger the on-disk-drive-hardware logic, but were visible looking in the raw (true raw) analog domain.
Sigh.
funny; it reminds me of Hellschreiber facsimile
https://en.wikipedia.org/wiki/Hellschreiber