Since it is PowerPC based with only 384 MB RAM, my Linux choices are restricted. Happily (I thought), Debian would do the trick. One of Debian's virtues is that they provide Linux for many less common machine architectures.
Read it here
Cut to the chase: The Keyspan usbserial driver for my device has been deemed “impure” by the Debian group. This driver passes all the legal and policy hurdles for Fedora and Ubuntu, but Debian seems to have a “one drop” rule. Any hint of restriction on a software module means it's not going to be in a Debian release. Apparently, the Keyspan driver uses code that carries a phrase like “only for use on Keyspan products”.