On Thu, 11 Dec 1997 dillema@acm.org wrote:

> Somewhere in the include files I found 230400 Bps as a standard terminal
> speed, it is however not accepted by stty or pppd. I noticed that the speed
> in termios.h is represented with an unsigned int value. Does this mean max.
> serial speed is 65565 Bps??? If so, I find it a bit strange that 115200 Bps 
> is accepted just fine, while 230400 is not... I'm just being curious here. 

Serial line speeds are indeed represented to the kernel termios ioctl
calls as unsigned integers.  However, they are represented in an
enumerated fasion, not directly.  That is to say, 300, 600, and 1200 baud
are represented as the baud rates 1, 2, and 3 respectively.  (This is just
an example and not quoted directly from the real header file.)  This
places a limit not on the highest baud rate that can be represented, but
instead on the maximum number of baud rates that can be supported.

-J