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How can

  • VHS cassettes.
  • MiniDV cassettes.
  • Compact audio cassettes

be used as digital data storage?

Can the error correction strength be adjusted?

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    It's not realy clear what you're asking for. All these have been used one way or another. Further asking for some 'adjustment off (whatever) error correction strength' is rather meaningless.
    – Raffzahn
    Commented Jan 14, 2018 at 17:23
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    I think it might be overly broad; e.g. micros have about a thousand ways of storing data on an audio cassette. Though here's an easy one: MiniDV is inherently digital. That's what the 'D' stands for.
    – Tommy
    Commented Jan 14, 2018 at 18:31
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    With the same of level of detail as in the question: Yes, they can, by encoding digital data as analog signals for the two analog media. And there are many, many ways to do that, and many, many ways to do error correction.
    – dirkt
    Commented Jan 14, 2018 at 18:35
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    If you want a serious answer, ask a question about a specific topic. Otherwise any answer will be as unspecific and therefore not realy a desired addition to the site.
    – Raffzahn
    Commented Jan 14, 2018 at 18:49
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    Recommend rephrasing the question in a way that makes its relationship to retro computing more clear. The way it's worded now sounds more like a question about digital signal processing theory, maybe more appropriate for dsp.stackexchange.com
    – snips-n-snails
    Commented Jan 14, 2018 at 20:07

3 Answers 3

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You can use these types of tape cassettes for digital storage by acquiring the correct kind of tape drive and/or interface for each.

For VHS cassettes the "tape drive" would be a standard VCR connected to a special interface card that converts digital data into analog signals that can be recorded as a video signal. These special interface cards aren't made any longer that I know of, but you might be able to find one used.

For MiniDV cassettes the easiest way is to get a MiniDV camcorder that has a FireWire (IEEE-1394) connection, then connect the camcorder to a PC that way. The camcorder will then appear to the PC to be a digital tape drive that can be used by software that knows how to work with tapes (and knows how to use IEEE-1394). I believe that certain versions of Microsoft Backup were able to use a MiniDV camcorder connected this way.

Compact audio cassettes were most frequently used for digital data with home computers in the 70's and 80's. Typical setups used regular commercial tape recorders connected to the computer using the earphone and microphone connections, with circuitry in the computer converting the analog audio signals into digital. Commodore used a special tape recorder that communicated digitally (the digital/analog conversion circuitry being in the tape drive rather than in the computer). There were also tape drives made that used very similar cassettes with a special notch that identified them as data-grade; audio cassettes could not be used with those drives.

In general, the error correction schemes for these methods is fixed and cannot be adjusted. If you need more error correction you can preformat your digital data with ECC, then write that preformatted data to tape. There is software out there that will add ECC to arbitrary data, this was typically used when transmitting data over some kind of network but it would work just as well for this.

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The VHS (and Beta) protocols required signals to mimic frames of television picture, so are hardware-supported in complex ways. Digital use (possible exception of PCM audio) was rare.

The CompactCassette trademark licensing requirements precluded audio-player-incompatible use, so modified cassettes were used for digital directly, OR audio-compatible encoding (like the Kansas City standard) was used for indirect digital recording through FM modulation. The modified cassettes were not CompactCassette labeled.

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There used to be a software on pre Intel Macs to backup on DV, it was called DVBackup.

Here's what data looks like:

enter image description here

(from http://www.imaging-resource.com/SOFT/DVB/DVB.HTM)

While the DV media allows to store GBs of data, it still inherits the downsides of the approach such as no random access and low throughput.

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