I want to make the screen have 16 pixel high characters.
Given I'm PAL
reg value 4 19 5 0 6 12 7 16 9 15 23 16
And well when I set it from BASIC doing sys CDCC commands from data it worked. When I do it from asm, not so much, sometimes it is fine, sometimes it just rolls, in z64K it gives me a rolling half height screen.
Is the register change order critical? Do I need to set some registers and wait until something then change some more?
Exactly no idea, but if you run the code, you can get very mixed results. In BASIC it seemed to always work, but then when I was experimenting with it and changing one param at a time it would get messed up. It seems odd as you would expect it to "sort it self" once it hit next VBlank either way, but this is the VDC we are talking.