PF> I don't know what "keyed", "keyup" etc mean.   Since 
 PF> I'm ignorant on this,  I can't decide if the standard 
 PF> com.sys would be appropriate.

 DE> Never. Unlike a telephone modem, a radio modem turns its carrier on

Then the reply is easier for me -- you're going to have to write (or get
someone to write) a DD.  It will be pretty easy to meet your timing
requirements in a DD.  



 DE> Thanks, I will look into that. The only concern that I 
 DE> have here about using a device driver is that I hear 
 DE> that a device driver can not access other device 
 DE> drivers.

This is not strictly true.  There is an IPC mechanism for DD's,  but it is
something specific to each DD.

   > As a routine, we log each individual
 DE> character to disk as it comes in / goes out the com 
 DE> port. This is critical for debugging field problems.

You can't just call the "disk DD" to have it log stuff,  as you
guessed. But you can, periodically (every 1k for example),  have an
application do the logging for you.  There is also the TRACE facilities
provided by the OS (see DevHelp_SysTrace).


--- Maximus/2 2.02p1