What do macs use as far as a UART chip on their serial
ports?

The problems I hear people having sound similar to
what I'm used to seeing on old PC's with an 8250 or
16450 driving the serial port.  An 8250 can't do
anything above 9600 and a 16450 isn't much better. 
But serial ports which use a 16550A or compatible UART
can run at 56k without any trouble.  This is because
these UARTS feature a 16 byte FIFO buffer so that when
the computer is busy and doesn't respond quickly
enough to the interrupt, the data doesn't get lost. 
I've got a 16550A based internal 33.6k modem that I
ran on a 386sx-16 with no problems at all, and this
was under win31.

If NetBSD simply isn't making optimal use of the
serial ports then that is one thing.  But if the
serial ports are just plain lousy, like what you'd
find on cheap ISA multi-io or IDE-IO boards for PC's,
then I don't know what can be done about it.  Are
there NuBUS based boards available that provide good
serial ports?

Lee Reynolds


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