[GreenKeys] GreenKeys Digest, Vol 62, Issue 34

[John Nagle]

> After some experimentation, I found like there is a probably a lower 
> baud rate limitation for serial ports on Windows XP of 50 
> baud. 

    Windows 2000 will run serial ports at 45 baud, and Windows XP
should, also.  The parameter to the Win32 call is an integer baud
rate; the driver just computes the divisor for the serial port.  Low
baud rates work fine.  This applies to serial ports on motherboards
and on PCI and ISA cards, not USB devices.

    Linux is more limited, because the Linux approach to baud rates
uses a set of canned baud rate constants based on what PDP-11 serial hardware
could do.  There's a program called "setserial" to get around this,
and "Heavy Metal" uses it.

    USB ports are another matter. The problem is that most USB to serial
devices don't support low baud rates.  This is apparently a bug in
common firmware, not an inherent hardware limitation.  See

"http://lists.contesting.com/_rtty/2008-02/msg00381.html"

The Belkin F5U103 has been reported to work at 45.45 baud, but that's
a discontinued product.

				John Nagle