Why?

The HP48 is a good platform for GPS (Global Positioning System) related programs, I think. It's small, sturdy, quite versatile, fun to program, and has excellent battery life and built-in mathematics capabilities. Plus there's the thrill (yes, yes, geekish I'll admit :-) of connecting your GPS to a calculator.

What's been done

I've written GxPS, which exchanges waypoints, routes, tracks, and other data with Garmin GPSs, and NMEA48, which is a stand-alone version of GxPS's NMEA support for those who don't need the Garmin protocol features. Both of these programs provide commands to return position, altitude, and time, plus other utilities to facilitate working with the Garmin and/or NMEA protocols. Hopefully these commands will make writing GPS-enabled programs easier on the 48.
Also, I've collected a few related links and a little information about building cables and cases, all of which you will find on these pages.

What still needs to be done

Here are some ideas people have suggested for GPS related programs. If you are working on something like this or would like to, please let me know!

Project Developer

GarMon 2.07b -- draws maps of waypoints/tracks and much more PCW

GxPS 2.1 -- support for more models, PVT, and other things Jason Grant

A graphical waypoint/route editor with support for icons and possibly different datums -

A program to upload/download waypoints from other GPSs (Eagle/Lowrance and Magellan) -

Other applications like a position averager/grapher or a flight/trip computer -