A simple universal modem allows data to be saved and loaded from tape
In the early days of the home computing revolution, data was typically stored on tape. Best of all, these tapes would make an almighty racket if you played them on a stereo, because the data was stored in an audio format. [Anders Nielsen's] Simple Universal Modem is designed to work the same way, turning data into audio and vice versa.
The project consists of a circuit to modulate data to audio and demodulate audio to data. It's "universal" because [Anders] designed it to be as format independent as possible. It doesn't matter whether you want to store data on a digital voice recorder, a tape deck or an old reel to reel. This version should work pretty well on all of them!
On the modulation side, it's designed to be as analog-friendly as possible. Rather than just spitting out rough square waves, it modulates them into nice smooth sine waves with fewer harmonics. On the demodulation side, it has an LM393 comparator which can read the tape data and spit out a clean square wave for easy decoding by digital circuits.
If you find yourself trying to recover old data from tapes or writing to them for a retro-computing project, this release might be just what you need. [Anders] even goes so far as to demonstrate its use with an old reel to reel set in a helpful YouTube video.
There were really weird ways to store data back then. Ask IBM. Video after the break.
In the early days of the home computing revolution, data was typically stored on tape. Best of all, these tapes would make an almighty racket if you played them on a stereo, because the data was stored in an audio format. [Anders Nielsen's] Simple Universal Modem is designed to work the same way, turning data into audio and vice versa.
The project consists of a circuit to modulate data to audio and demodulate audio to data. It's "universal" because [Anders] designed it to be as format independent as possible. It doesn't matter whether you want to store data on a digital voice recorder, a tape deck or an old reel to reel. This version should work pretty well on all of them!
On the modulation side, it's designed to be as analog-friendly as possible. Rather than just spitting out rough square waves, it modulates them into nice smooth sine waves with fewer harmonics. On the demodulation side, it has an LM393 comparator which can read the tape data and spit out a clean square wave for easy decoding by digital circuits.
If you find yourself trying to recover old data from tapes or writing to them for a retro-computing project, this release might be just what you need. [Anders] even goes so far as to demonstrate its use with an old reel to reel set in a helpful YouTube video.
There were really weird ways to store data back then. Ask IBM. Video after the break.
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