Linux/RTLinux/RTAI Supported I/Fs

[Russ Swatek <swatekr@kmrmail.kmr.ll.mit.edu>]

We are embarking upon a port of several existing capabilities hosted on
legacy H/W and OSes to an Intel Pentium PCI-bus based realtime Linux
platform.  So the search for I/Fs with some level of existing (realtime)
Linux support begins.  We will need:

  4 RS-232 I/Fs
  8 16-bit parrallel (used uni-directionally)
  2 8-bit parrallel (used uni-directionally)

We are free to select whatever motherboard and I/Fs required.  Only some
of the serial I/Fs and 16-bit parrallel I/Fs need realtime response. 
One thought has been to have duplicate boards of each I/F type, one
controlled by standard Linux and one controlled by realtime S/W.  Our
application is more noteworthy for the number of devices to which it
interfaces, and not the I/O or number crunching throughput.

Are there any thoughts about preferred equipment choices for the above? 
Of course, we would like existing (realtime) support as much as possible
:)

Thanks,
Russ Swatek
Raytheon Range System Engineering
Kwajalein Atoll, Marshall Islands