And speaking of HP LX palmtops, here's my 100LX. Yes, that's Windows solitaire, not even the WinCE version. This device is in fact a PC XT disguised as a 90s PDA, and it can run Windows 3.0.
@ari Actually a few weeks to a month on 2 AAs depending on usage. The processor is a low power CMOS 80186 and the hardware is generally optimized for saving energy. HP was very good at that, an HP 48g calculator will run for years on 3 AAAs, compared to maybe one year on 4 AAs on a TI-83.
The omnigo has a lower resolution screen, and runs geos by default. It uses the same serial cable. It can do textmode dos stuff, but it takes digging through archives of German websites to find the appropriate software.
I'm working on putting together a complete toolkit with instructions but that'll be a few weeks down the road.
The serial cable, though, is pretty easy. You can rig one up with some jumper wires and some electrical tape.
Eventually, I'll get a pair of calipers after one of mine, and post the exact dimensions (and possibly an STL) for 3D printing your own.
Until then, the pinout is pretty easy to track down, and the pins are the exact width of standard jumper wires.