serial port real versus effective speeds

["A. R. Vener" <salt aero-vision com>]

Hi,

I'm giving emacspeak a rest for now after many long
and frustrating hours with it. For me the learning
curve is not worth the loss of productiveity I'd have 
to endure until I figure out all its idiosyncrasies.

I've finally set up my Caldera system to use a serial
port to connect to a DOS box running Telix and Vocal Eyes.

After several false starts this process finally boiled down
to the following step:

Edit the /etc/inittab file and add this line after the
existing getty lines:

s7:2345:respawn:/sbin/getty /dev/cua0 default vt100

s7 is just a unique tag name I picked basically out of the blue, I was going
  to use s0 until I discovered another inittab line used it during startup.

default - is the name of an entry in /etc/gettytab, this is where
  the serial port parameters such as baud rate is set.
vt100 - termcap entry



This seems to work. For some reason I haven't yet figured out, the
/dev/ttys0 device does not work, although all the documentation I've
read said to use ttys0 for DOS com1 and ttys1 for DOS COM2. 
Does anyone know why this is so?  I stumbled across the 
/dev/cua0 device name when I was reading the setserial manual
page.


This brings me to another problem.  Although I can set the Linux
port and Telix ports to the same speeds and everything works, there
seems to be some sort of delay introduced which reduces the 
effective transfer rate to under 9600 baud.  This happens regardless
of the actual speed to which I set the serial ports. It is obvious that
the ports are using the correct bit rates since  I only get the login prompts
and a working connection if I match Telix and to the Linux serial port. But
even at 38400 a screen refresh takes several seconds.  Has   Has  anyone 
encountered this problem and fixed it?

Also, is there a way to set up Linux so that it uses the serial port as 
its console during boot?  I'd like to be able to trap the boot up messages.

Thanks,

Rudy