Very interesting. I didn't know about these layers, and it's very different to how I conceptualized and tried to use bitmap graphics on my home computer.

I spent a big part of my childhood both playing coinops and also envying their awesome -- to me -- graphics. They looked so far beyond what my C64 and even my first PCs were capable of! To learn they actually ran on quite underpowered hardware was such a big reveal. Underpowered but dedicated, I guess that was the secret.