"pilot" wrote in message
oups.com...
Thank you Meindert,

it clarifies the hardware part. Now, for
the software : can a normal computer (800 Mhz) handle serial data
coming at 488 bauds from a gps, and an other one, coming at 38400
bauds, from an AIS port, at the "same time " ?

Easily!!
Example: our multiplexers handle 6 channels at the same time, 4 at 4800
baud, 2 at 38400 and 57600 respectively. And all on an 8MHz processor. I
have run 486/66 computers with serial ports at 375,000 baud without a
problem.

Since I will probably take only the lat &
long, HDOP and number of sat's from the GPS, I will leave all
satellites related sentences (GPGSV) aside. Do you think I will be
better to do some timesharing between the ports, or let them fire the
comm events whenever they happen, no matter where they are from, I mean
from one port or the other ? I have never tried anything of this
nature. That's why I ask.

There's no such thing as timesharing between com ports. You open two
comports and you either run a task/thread per com port or you run a fast
loop that periodically calls readfile() to get any buffered characters. The
com port drivers in Windows (do you run windows ?) buffer a few kb of data.
But the best way is to run a thread per com port and let each thread
assemble characters into a complete sentence and then create a message that
passes a pointer to the sentence, which is handled by the main task of your
program. To play it safe, you can implement a sentence queue but you'll find
this queue get's hardly filled up unless the main part of your software is
terribly slow at updating charts, for instance.

Meindert