How do I check old ZX spectrum cassettes work - the tapes are after all quite old?

I am fairly computer savvy (my life is a continual strand from that Speccy to this here Thinkpad - and many stations between :-)) and I have a mono cassette player so I figure I can sample the tapes to something like *.tzx and load them into an emulator. Is this really necessary? If it is necessary, is there a quicker way of determining whether the software is still OK?

  • is this your personal work? or software you can find somewhere else (already dumped) ? sampling+converting to tape format wouldn't see all errors probably (there is few or no error checking on tapes) – Jean-François Fabre Feb 11 '20 at 15:42
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    It's a bit of both though mainly the later. The former is probably so dreadful I'm kinda in two minds if I wanna see it again ;-) – NickM Feb 11 '20 at 16:43
  • @NickM see What should be the waveform for ZX Spectrum tapes? – Spektre Feb 11 '20 at 17:27
  • It ought to be possible to sample the tape, then do some kind of analysis to determine whether the tones, bit spacing and so on are within spec. Maybe even do some deep inspection by making sure the data all makes sense for the target platform (no invalid opcodes, etc.). – snips-n-snails Feb 11 '20 at 18:40
  • Thanks for the comments and, as is often the case with SE, it has set me off on a new tangent as well. There may be a few Fourier transforms in my near future. – NickM Feb 11 '20 at 22:19

I guess some emulators have a direct MIC input for a quick check, but I prefer a little bit longer way.

First of all, I connect the tape with the PC (in fact, I have a "USB Walkman") and make a digital copy using Audacity, at the best quality I can (48 kHz sampling frequency, 16 or 24 bits). Save it as lossless WAV (NO MP3!)

With this record, I can do all necessary operations, e.g. cutting, speed corrections, filtering, volume correction ... The only thing you cannot fix are the dropouts. Dropout = dead. (But you can fix dropout in the leader tone if you need.)

The last step is to use any WAV to TAP / TZX converter. At this phase, you will get the digital version, suitable for archiving - or get a STOP sign, back to the Audacity, do something, try again...

Definitely a nice work for a weekend! :)

  • I'm curious why you said no MP3. Does data not encode/compress well? – Ben Hillier Aug 24 '20 at 9:57
  • @BenHillier I believe that the "master record" should be saved with no losses. Later you maybe use MP3 with sufficient bitrate, but you still have the master in the best quality available... – Martin Maly Aug 24 '20 at 10:19

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