Was wondering what the palette-looking dots at the edges of some Mega Drive frames were, looks like they’re known as “CRAM dots;” they’re an artefact of the palette RAM being accessed, particularly if they’re being changed via DMA! http://md.squee.co/VDP#Palettes http://gendev.spritesmind.net/forum/viewtopic.php?p=1871#p1871
it seems that when they’re at the bottom of the screen, it means the CRAM was updated during blanking, while if they’re at the top the CRAM was updated during drawing