Glitches on Higher Level (1992) demo by Lower Level about vicii-kawari HOT 1 CLOSED

Okay, so believe it or not this is actually due to the KERNAL version. ROM versions kernal.901227-01 and kernal.901227-02 will glitch out as you reported but kernal.901227-03 does not. It has to do with the way the screen clear routine works. (I don't remember the exact details but it has to do with setting the color cells to the background color instead of the foreground).

So this demo is probably expecting the behavior of rev 3 . If you run VICE with versions 1 & 2, you will see the exact same glitches you reported. By default, VICE gets rev 3 so that's why I didn't see the glitches. Those stray pixels are there even in rev 3 but they are black so you don't see them.

I've been caught by this difference before. The Galencia game disk has a trainer that prompts you to answer 3-4 Y/N questions. But on the older kernel revisions, you get a black screen. It looks like it crashed but it's actually just waiting for you to answer questions you can't see. But on rev 3, you see the questions.

I tried the demo on Kawari on a REV3 kernel and it renders properly.

from vicii-kawari.