"Stefan" wrote in message
. ..
Why shold that matter? I find it just plain crazy that 166 MHz shouldn't
be enough for a plain simple data transfer over a serial line.

But then, I've just seen that Michael wrote 166 mHz. Now this may be
marginal, agreed.

It is enough.

However, I have found that not all serial devices are the same and what
should work in theory does not always.

For example, I have some pinball machines that use a serial connection to
update the firmware. Unfortunately, I could just not get the update to work
correctly with a newer computer. I had to actually downgrade to a slower
one for things to work.

It wasn't a performance issue. It was a basic difference in timing issue
somewhere, in which the slower computer didn't manifest the problem but the
faster one did.

I was later able to modify the firmware updating software so that it could
deal with the subtle timing difference and run on faster computers (the
timing difference generated spurious bytes on the serial line, and the
update software wasn't doing enough error checking to accomodate the
errors). But if I hadn't had access to the source code, the easiest option
for fixing the problem would have been to simply use a different computer.

Just as is the case here. It's unlikely that the difference between the
166Mhz and 3Ghz PCs is specifically related to a performance requirement.
It's much more likely that there's just something different about the slower
computer that was never tested or discovered by Garmin when they were
writing the update software (probably because there didn't seem to be a need
to). Using a different speed computer makes the problem just go away.

Pete