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We used to use regular audio cassette recorders to store/restore data on the TRS80 before hard/floppy drives. It's also how you backed up/restored midi data fro

• bobleeswagger 4y ago
  > It basically just sounded like an early dial up modem transmitting data when you played it back as audio. Modern synths still do this. The Korg Volca has a library for converting audio into white noise that reprograms/adds more samples.
• noizejoy 4y ago
  > It's also how you backed up/restored midi data from early synths. In a weird closing of the circle, I now store the internal sounds backup of my vintage Juno 60 synthesizer as a WAV file recorded from that tape backup output. So the digital info of the internal synthesizers gets converted to analog audio in the synth, then passed as audio to my modern computer’s audio interface, which converts it to a digital representation of the analog audio. And vice versa to restore the backup into the synthesizer’s memory. Incidentally those backups are more reliable now than when using analog tape decks, since one doesn’t encounter physical tape degradation or a cassette deck “eating” the tape. I haven’t done any testing with compressed audio formats, but I would expect even lossy formats to perform well, if one keeps the lossiness within certain bounds, so that the highest frequencies in the audio file are preserved.
  • Someone 4y ago
    > I haven’t done any testing with compressed audio formats, but I would expect even lossy formats to perform well, if one keeps the lossiness within certain bounds, so that the highest frequencies in the audio file are preserved. MIDI as a compression format for that kind of audio data would be a lossy way to encode such an audio stream, and it certainly would perform well, so yes, such lossy formats do exist. Most research in audio compression has been done on compressors that exploit the limits of human perception, though, so of the shelf lossy compressors may not do very well.
    • DontchaKnowit 4y ago
      Calling midi a form of lossy audio compression is a stretch. Its like saying whistling a tune is a lossy way to compress a song. Yeah you're transmitting information about the source but to call it lossy is an understatement.
• chiph 4y ago
  My Apple ][+ had a tape interface. It mostly worked - if the tape stretched or if the tape speed changed for some reason (dirty capstan, power supply fluctuations, low volume, high volume, evil pixies) then you wouldn't be able to read it back. This site describes the format, which was basically a header tone, a sync tone, data bits, and then a checksum (not described there but other sites say it was just an XOR). When we got a Disk ][ (5-1/4" floppy drive) all those issues went away. http://www.applevault.com/hardware/apple/apple2/apple2cassette.html http://www.applevault.com/hardware/apple/apple2/apple2casset...
• ta1243 4y ago
  How you loaded games onto my Spectrum 48k, had to make sure the volume on the output wasn't too high or too low. I could guess it had a bandwidth of about 2-3kbit from how long I think it took to load (nearly 40 years ago)
  • Gordonjcp 4y ago
    It varied with the content - a zero had a high-pitched tone and took half as long to transmit as a one - but it averaged out at around 1800bps. Certain things had really distinctive sounds, like loading screens. I could recognise Manic Miner loading from just about any ten second chunk.
• michaelcampbell 4y ago
  Atari too; and god they were unreliable. But cheap!