Found it: http://blog.moertel.com/posts/2013-12-1 ... -hack.html (it's 6809)
Cheers
Ed

Nice link, Ed! The 6809 can be quite versatile in the hands of a true 8-bit hacker, but the technique described is very closely coupled to the 6809 architecture. Although I always somewhat admired the 6800 as "the grand-daddy" of all the 6xxx family (with which my brain feels the most comfortable) it can't be ignored that its instruction set can be brutally inefficient for some of the simplest tasks. Another example is pushing and pulling the X register:

The 6809 equivalents would benefit by at least an order of magnitude from the availability of the U register, with a simple pshu X and pulu X.

Similar things can be stated regarding 6502 vs. 65802. Garth and saipan59 discussed this at length here, but the best message that I got from it is that the updated versions of each family were much improved from the originals, in a variety of ways.

Mike

Because I landed on the previous page and had forgotten that I'd found the lost article, I went looking again. And found something similar for the Z80 in the Spectrum, for the game Starion, by David Webb, apparently. There's an interview with him here.