Has anyone had any luck setting one of these Digi Board pc/8 16c550 boards in Ubuntu 8.04 server?

using page 63 of this document http://ftp1.digi.com/support/documen.../90029700a.pdf i am able to see 4 of the 8 serial ports.

I searched the forum for a related documents but came up short.

Is there some kernel hacking involved to see the other 4 ports?

Thanks for reading.