This scheme is strikingly similar to the Commodore Amiga's HAM (hold-and-modify) display mode. https://en.wikipedia.org/wiki/Hold-And-Modify https://en.wikiped

This scheme is strikingly similar to the Commodore Amiga's HAM (hold-and-modify) display mode. https://en.wikipedia.org/wiki/Hold-And-Modify https://en.wikipedia.org/wiki/Hold-And-Modify