[sebhc] H8-5

William Elkins bill at elkcomm.com
Mon May 22 20:45:36 CDT 2006

While it is true the audio from a cassette player is not synced the
waveform that was recorded on the cassette was. Bit transistions
occured at zero crossing on the carriers. If your clock and pc uart
are running independantly your bit transistions will rarely occur at
zero crossing. At 1200 bps the available number of carrier cycles per
bit of data is one or two depending on which state the data line is
in. At 300 bps you get 4 cycles or 8 cycles and the phase relationship
between the clock and the data is less important.


> At this point, all I'm trying to do is make the H8-5 think something
> else is a cassette player.
> I'm trying to feed the H8-5 AUDIO INPUT with tones just like the sound
> coming from a cassette player.
> The audio from an actual cassette is not sync'd to anything. The PLL on
> the H8-5 creates the clock from the audio coming from the cassette player.
> I haven't started to try to create the WRITE half of the project yet.
> I'm still just trying to make the H8 think I have an actual cassette
> player with a tape to load in it.
> Carroll

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