As I recall, on the Commodore 64's text mode, if you chose certain colour combinations, the letters would be badly obscured by some kind of interference which seemed to affect each character cell individually. If you put a yellow
A atop of a blue background, it would put several yellow pixels inside that character cell beyond the ones which made up the
Other combinations looked well, some reasonable, some terrible. I had around three different Commodore 64s from different batches, revisions, which all exhibited this problem, all connected by RF to a small cheap TV.
Yellow on a blue background would be the worst affected, green on a blue background would be somewhat better, and light blue on a blue background would be splendid and clear. White or greys on a black background also would be clear. I'm sure I'm not misremembering the fact this happened, but I find VICE doesn't seem to emulate it.
Why did certain color combinations cause bad interference in the textmode on the C64?