Than You Meindert,

How I can find if the "high speed" of 276C is 38400 or 9600?

There is a way to test the 276C with a file containing records of AIVDM
messages sended by an AIS receiver, and re-sending this messages to
the serial port of the laptop, using a program like Windows
Hyperteminal, so that the 276C woud read them again simulating a real
AIS receiver?

What the "unknown" guy said was:

" Then I think you schould start reading again.

All DCS capable Garmin receivers are also AIS capable.
DCS is still the most wideley spread system, and AIS does not add
anything to Garmin GPS receivers over the DCS system.

You can easely combine a Garmin with DCS with a AIS reciever since the
data send to the (external) gps is exactly the same"

This made me suspect that he could have some confidential information
about AIS and 276C and that the actual standard firmaware (3.20) maybe
is already able to receive AIVDM messages and get ships's MMSI, name
and position (at last), wich would be a proof that Garmin is already
developing the software (and maybe some hardware) for AIS on some DSC
ready gps receivers, like my 276C

Regards

Pascal