more VIC-II musings

From: Michiel Boland <*michiel_at_boland.org*> Date: Mon, 13 Jan 2020 20:55:50 +0100 Message-ID: <30a2f151-b5fd-bd99-850f-855717730962_at_boland.org> · michiel_at_boland.org

Hi. Not sure if this has been mentioned already, but there is a bug in the 
VIC-II chip where it will simultaneously shift a sprite shift register and 
attempt to load it with a new value at the same time, for the duration of one 
pixel. This introduces some interesting phase-of-the-moon bugs in combination 
with multi-color mode. At least, that what I think is going on.

https://youtu.be/BN8LQz7aBLg

As an aside, there appears to be some work here and there of people who have 
reverse-engineered, or have tried to reverse engineer the VIC-II chip based off 
of die shots. But there does not appear to be anything definitive online (a la 
visual6502), or it was once there but has since disappeared. Or maybe I am 
looking in the wrong places. What is there to be found regarding this? (So I 
don't have to reinvent the wheel. :)

Cheers
Michiel