A software thing I built: GPS on a 25MHz 486-SX
A software thing I built: GPS on a 25MHz 486-SX. A software thing I built: GPS on a 25MHz 486-SX Thread starter spd Start date Yesterday at 9:57 PM S spd Member Joined Aug 29, 2026 Messages 12 I don't know if anybody cares about stuff like this, but I thought I'd share a quick story about a project I was hired to build back in the 90's as an embedded systems software developer.
What happened
I was asked to write this software so it ran on a hardware platform with a 25MHz 486-SX CPU, 32MB of RAM and the software would be in ROM. It's something I worked on where I was asked to build a "real-time GPS-driven moving map display" — what we simply call a "GPS" today. Only today it's built into virtually every cellphone and tablet computer in the world. At the time, all of the math stuff I could find for GIS applications was built around heavy use of floating-point numbers and lots of trig formulas. (My BS was in Math/Computer Science. ) As it happened, a few months before that, an article was published in Dr.
I built a prototype with the code from that article, and was surprised how well it worked. I had the client buy a copy of the Hipparchus library and built a fully-working model. But it wasn't until 1989 that a lawsuit between Apple and Franklin computer resolved things in favor of the "clean-room" approach.
The wider picture
And, what I had built was twice as fast as those first-gen devices! It was literally 10 years before anybody had a consumer-grade GPS that had similar performance to what I had built in 1993 that did not require a math co-processor, and it updated a 1024×768 color display every 2 seconds. New posts Search forums Menu Log in Register Install the app Install How to install the app on iOS Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers. Please review our updated Terms and Rules here Forums Companies IBM Computers, PCs, Clones and Descendants 386/486-based Systems You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser. This is a project I wish I still had access to.
What has been reported
They gave me a laptop configured like that for testing. The 486-SX was the one without a math co-processor. Dobb's Journal about a library that took a very different approach. It was called Hipparchus from a company named Geodesy. It used Voronoi Cells and reduced most math to 8- and 16-bit integer calculations with one or two single-precision floating-point calculations. It actually had higher resolution than Extended-precision floating point math! The client ran into some financial issues and I had to turn over all of the stuff to them.
I have no idea what happened to it after that.
What happens next
They could have become a billion-dollar business. Curiously, someone caught wind of what I had done and contacted me directly to see if I could do that for them. Unfortunately, I was just a contractor and didn't own the IP. It's worth mentioning that Phoenix Technologies took a "clean-room" approach to building their own BIOS for IBM PC clone vendors to use, and they never got sued for it. Unfortunately, I wasn't aware of this stuff in 1993, or I would have known to simply start over with the specs.
Anyway, this was 5 years BEFORE anybody had ever seen a consumer-grade GPS device from Garmin or Magellan. The big problem they had was. . . it took that long for an inexpensive CPU with sufficient floating-point speed to run traditional trig algorithms.