Modern formulations are proprietary and almost certainly require a cleanroom, but the basic concept has existed for a century. I’d assume there’s a history out there beyond what little Wikipedia offers.
Would I be able to DIY a tape that could store tens of megabytes of data, at least?
Edit: This adjacent wiki might have more to say on it, based on the reply I got. I assume digital data amounts to a much higher frequency of recording, though.
I do know audio cassette tapes were used repurposed for digital storage in the early PC era. Was there a noticeable difference based on quality and type of tape?
Depends on a couple different factors such as how robust you want the data encoded and the length of the tape.
Assuming 1mm thick tape encoding 11 bits (8 data, 3 error correction) per row at about 1mm wide and 10 meters of tape; you could store 10MB robustly. Higher density is more difficult but entirely possible.
Hmm, all the way up at 1mm. Man, that tape length really adds up, doesn’t it? So, to the question exactly as I asked it, I guess obviously yes.
Maybe I can do even better then. If I’m also building the head, the dielectric gap that does the reading and writing can probably be as small as tens of microns, since you can fairly easily make an edge that fine. Keeping the tape clean and even enough to not crash would be hard in that context, though, since it seems like clearance needs to be on a similar magnitude. Does anybody know what consumer tape reader/recorders use?
In tape form getting an even layer of medium might also be challenging, although if I went with a disk instead it could be spin-coated. Highly oriented particles sound doable with a bit of chemistry.
I’d upvote this, but ironically it would make it look like I didn’t upvote it.