You have also a Nick from "bad" series, the noise and the extra characters at the bottom of the screen shows that, my EP has also this kind of Nick chip, some speccy conversions had this noise which did not have black border, and showed the extra characters also (for example in Turbo Esprit, and there was noise and jumping screen in The way of the exploding fist, now I remember only these 2 games)
I think the border effect is not fix on the side, because timing problem in the code.