In 1982 Columbia Software released Roadsearch and Roadsearch-Plus for the Apple II, which is quite possibly the first software program (at least for consumer home computers) that contained a basic nationwide road map of 406 cities and could generate an itinerary from point to point - Google Maps but a bit slower. :bigass: In 1984 it was ported to the Commodore 64 and apparently had an update in 1985 to 487 cities.
Since I'm also a computer geek, I decided to reverse-engineer it. I did a bit with the Apple II release but spent most of my time on the later C64 one because of the more recent highway database. I altered the DTL-64 BASIC Jetpack runtime library to let me break out of the program and then extracted its database and analyzed its algorithm and use of arrays. It actually implements a fully-functional A* path traversal algorithm and does so surprisingly quickly for small 6502 systems.
I also stress-tested it with cross-country drives and my own first long haul to British Columbia on US 395, and it not only computes the path successfully, it does so optimally. I've thrown in some gratuitous highway scenery shots so not all of you will be completely bored. ;)
https://oldvcr.blogspot.com/2025/08/make-your-apple-ii-or-commodore-64.html