Again in the early days of the residence personal computer revolution, details was frequently saved on tape. Even superior, those people tapes would make an almighty racket if you played them on a stereo, because the knowledge was stored in an audio structure. The Basic Universal Modem from [Anders Nielsen] is crafted to do the job in a very similar way, turning information into audio and vice versa.
The task consists of a circuit for modulating data into audio, and demodulating audio again into facts. It is “universal” because [Anders] has made it to be as structure-agnostic as doable. It does not make any difference regardless of whether you want to keep facts on a digital voice recorder, a cassette deck, or an aged reel-to-reel. This establish must operate rather effectively on all of them!
On the modulation side of issues, it’s made to be as analog-pleasant as probable. Alternatively than just spitting out tough square waves, it modulates them into pleasant smooth sine waves with less harmonics. On the demodulation aspect, it’s bought an LM393 comparator which can go through info on tape and spit out a clear sq. wave for simple decoding by electronic circuitry.
If you discover your self making an attempt to get better old facts off tapes, or producing to them for a retrocomputing challenge, this develop may be just what you need to have. [Anders] even goes as considerably as demonstrating its use with an outdated reel-to-reel deck in a valuable YouTube online video.
There truly have been some odd strategies of storing knowledge way back when. Just inquire IBM. Movie right after the crack.