tape "load and save" to a PC/Mac
hp-fix at xs4all.nl
Wed Nov 18 03:37:16 CST 2009
> -----Oorspronkelijk bericht-----
> Van: cctalk-bounces at classiccmp.org
> [mailto:cctalk-bounces at classiccmp.org] Namens Cameron Kaiser
> Verzonden: woensdag 18 november 2009 7:37
> Aan: cctalk at classiccmp.org
> Onderwerp: tape "load and save" to a PC/Mac
> I'm working on a Tomy Tutor tape decoder because, well, no
> one else is. To that end, this weekend I managed to crack the
> encoding and now have a primitive tape decoder that reads an
> AIFF audio file and spits out bits for a higher-level decoder
> to process. To date I can now see the bit pattern for the
> GRAPHIC paintbox, and can even do rudimentary decoding of
> BASIC programs.
> So far so good.
> However, playing back that exact uncompressed 44.1kHz 16-bit
> mono AIFF into the Tutor doesn't work (before you ask, the
> Tutor's tape inputs are mono).
> The Tutor doesn't see the sync mark, and never loads the
> "tape." I recorded this a few times, making sure that all the
> output got on the audio file, and no dice. I also played with
> line levels and varied the output volume level through all
> the fine steps the Mac would let me step, and the Tutor just
> sits there.
> Have people discovered any gotchas in general about using PC
> audio files to load and save from tape, besides the obvious
> ones like don't compress, etc.? Any suggestions about how to
> make the Mac's output more acceptable to the Tutor?
> ------------------------------------ personal:
> http://www.cameronkaiser.com/ --
> Cameron Kaiser * Floodgap Systems * www.floodgap.com *
> ckaiser at floodgap.com
> -- Adore, v.: To venerate expectantly. -- Ambrose Bierce
I suppose the Tomy Tutor uses FSK or something like that as codec.
You should find out the base frequentie and use a (analog)low pass filter to
filter out any spikes and smoothing the signal. Old cassette tapes have a
band pass between 200-6000Hz (10k for metal tapes) using a filter would
smooth the signal with more change for succes.
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