Back at work now, I can look up the multiport board info.  First
off, Boca Research (+1 407 241 8088) makes a series of multiport boards.
These include the

        BB1004  4 port board
        BB1008  8 port board
        BB2016  16 port board

        Each port is similar to 1 16550 and takes 8 bytes of I/O space.
All ports drive one interrupt line and a status byte is available with
flags from all ports.

        The other board I've used is the GTek PCSS-8I.  GTek can be
reached at +1 601 467 8048.  This board includes its own processor,
firmware and RAM.  It dynamically allocates buffer space in RAM to the
ports, as needed.  The standard board comes with 32 K RAM.  The board
uses 4 registers in I/O space.  A large number of commands are used to
send and receive data, select which port to use, etc.  In many
applications interrupts are not required, since the board buffers the
data for you.  Just poll the board.  The board does support interrupts.

        Each of these boards also come with drivers to support a variety
of operating systems.


Harold