Back again in the early days of the property personal computer revolution, details was generally saved on tape. Even superior, these tapes would make an almighty racket if you performed them on a stereo, since the info was saved in an audio structure. The Basic Common Modem from [Anders Nielsen] is designed to function in a very similar way, turning info into audio and vice versa.
The challenge consists of a circuit for modulating data into audio, and demodulating audio again into details. It is “universal” for the reason that [Anders] has made it to be as structure-agnostic as doable. It doesn’t make any difference regardless of whether you want to retailer details on a electronic voice recorder, a cassette deck, or an outdated reel-to-reel. This develop really should function reasonably very well on all of them!
On the modulation side of issues, it is designed to be as analog-pleasant as doable. Instead than just spitting out rough square waves, it modulates them into pleasant smooth sine waves with less harmonics. On the demodulation side, it’s obtained an LM393 comparator which can go through knowledge on tape and spit out a clean up sq. wave for simple decoding by electronic circuitry.
If you come across yourself making an attempt to recover outdated information off tapes, or producing to them for a retrocomputing undertaking, this establish may well be just what you have to have. [Anders] even goes as much as demonstrating its use with an old reel-to-reel deck in a valuable YouTube video.
There actually had been some weird ways of storing facts way back again when. Just ask IBM. Movie after the crack.