Hi Thomas,
Welcome to [stella]!
> That helped. It may even be sufficient... sort of. But now I've noticed
> something else that has me wanting to know how it's done: both Mr. Do and
> Ms. Pac Man have single-pixel vertical resolution to their sprites!
>
> How the heck did they fit that in? You can't change both GRP0 and GRP1
> to the appropriate rows of two arbitrarily positioned and distinct
> sprites between WSYNC and the end of horizontal retrace. No way.
> Uh-uh. You just... can't.
I haven't looked at Mr. Do and only spent a little time in Ms. Pac-man so
bare with me.
In Ms. Pac-man player 0 is VDEL'd to achieve this.
So the scan line before doing the positioning GRP0 is loaded with its sprite
data. Then when it gets to the positioning code GRP1 is loaded with its
sprite data which will also draw GRP0.
There are a number of discussions in the archives about VDEL. Here's just
one from Eckhard
http://www.biglist.com/lists/stella/archives/200307/msg00124.html.
Take care,
Dennis
