Back again in the early times of the property pc revolution, facts was normally saved on tape. Even much better, people tapes would make an almighty racket if you played them on a stereo, simply because the knowledge was stored in an audio structure. The Straightforward Common Modem from [Anders Nielsen] is developed to perform in a identical way, turning information into audio and vice versa.
The challenge is composed of a circuit for modulating info into audio, and demodulating audio again into facts. It’s “universal” because [Anders] has created it to be as structure-agnostic as feasible. It doesn’t make any difference no matter whether you want to retailer facts on a electronic voice recorder, a cassette deck, or an previous reel-to-reel. This construct must work pretty effectively on all of them!
On the modulation side of things, it is intended to be as analog-pleasant as achievable. Alternatively than just spitting out tough square waves, it modulates them into wonderful smooth sine waves with less harmonics. On the demodulation side, it’s acquired an LM393 comparator which can read data on tape and spit out a thoroughly clean sq. wave for easy decoding by electronic circuitry.
If you discover oneself trying to get well previous info off tapes, or writing to them for a retrocomputing project, this create may well be just what you need to have. [Anders] even goes as considerably as demonstrating its use with an aged reel-to-reel deck in a useful YouTube video.
There genuinely were some bizarre methods of storing information way back when. Just check with IBM. Online video following the crack.
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