PetSpeed dongle

Hi all,

I have been trying to do some research into the dongle for the PetSpeed
compiler (compiling PET Basic). From what I gather, if you don't have
the dongle, the compiler always exits with "disc error for <filename>:
01, ok, 00, 00, 1". That is, if you give it an existing file name to
compile.

From what I gather, it uses CA1 (cassette #1 read line) as input for
bits to a shifter (MSB first).
Cassette sense #1 is set to output to supply a clock.
At the start, cassette write #1 is toggled 1 -> 0 -> 1 as a reset signal.

The code seems to shift some bits in, but it isn't clear which value it
expects. The code (obfuscated, of course) checks for values #$AA and
#$FE as some sort of special case, but it seems that supplying those
values doesn't make it work.

The dongle seems somewhat similar to the WordCraft dongle, except that
it uses different lines on the cassette port for reset and clock.
For reading the bits in it uses the same cassette read signal, and
because it is edge-sensitive, uses the same trick of toggling the
"active transition" direction whenever an "active transition" happens.

The code starts at $14AD which is located in the file "scan".

Does anyone have a dongle at hand and can supply more information?

-Olaf.
-- 
___ Olaf 'Rhialto' Seibert                            <rhialto/at/falu.nl>
\X/ There is no AI. There is just someone else's work.           --I. Rose