Holy crap! This takes me back. I used this (or something based on it) on my TI84 SE+ to play around with grayscale over a decade ago. It's the first thing that came to mind when I saw this article. I never got into ASM on the TI calcs but I wrote a TON of TI-Basic. I spent a ton of time on those forums and posted a number of apps/games I wrote (though I can't find them now).