After expermenting a bit for several hours deleting and reinstalling my Ubuntu virtual machine on the iMac, I have come to the conclusion that the following steps allow for the successful compilation of Thomas Okken's code:
1. Install Ubuntu 7.04, and when prompted install the updates.
2. After reboot, in Synaptic Package Manager search for and select: libgtk2.0-dev, lesstif2-dev, libxpm-dev, and libxmu-dev.
3. After installation of these packages enter either the motif or gtk subdirectories of the free42 directory tree and make the binary version by simply typing "make", and the decimal version by "make -e BCD_MATH=1".
I have found that using the lesstif package seems simpler than motif since the package manager in the former case seems to magically install as well some necessary X Windows development stuff that Motif does not. You have to find and install them manually, and in the spirit of overkill I probably grabbed a bunch of disk wasting stuff I don't need since I don't know for sure what is needed. Instead, choosing the above 4 dev packages above will select a total of about 40 packages that seem to be a minimal installation required to compile this excellent program in this flavour of Linux.
Thank you to Thomas and others for guiding me in this little adventure, and for the forebearance of the forum in indulging this discussion that is at best incidental to its main mandate of "real" vintage HP calculators. I hope other newbie Linux programming amateurs who start out with something like Ubuntu will benefit from my recent adventures.
Les
Edited: 17 Aug 2007, 12:34 p.m. after one or more responses were posted