[Coco] Cassette data format

[jens]

> The code doesn't output exactly 1200Hz or 2400Hz. The read routines
> are fairly tolerant, so it's not too big a deal.
>
>
> /* The "ideal" pulse widths vary according to where they are:
> *
> * Leader cycle: 68 + n0 * 28, 5 + n1 * 28
> * First byte cycle: 81 + n0 * 28, 5 + n1 * 28
> * Subsequent byte cycles: 120 + n0 * 28, 5 + n1 * 28
> * Other bit cycles: 67 + n0 * 28, 5 + n1 * 28
> */

I have added a analyze function in PyDC, to display zeror crossing timings in 
wave files (See: viewtopic.php?f=8&t=4231&p=8980#p8980 )

I will collect some WAVES here: 
http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=8&t=4326

Seems that the real frequency is about 1000Hz and 2000Hz