The cells were split into an even grid because that's how the video chip was designed. There was no other grid size and no customization. There was no room on t

The cells were split into an even grid because that's how the video chip was designed. There was no other grid size and no customization. There was no room on the silicon to do other grid sizes. There is no graphics API in the Commodore 64. You programmed the hardware directly in assembly. If you wanted an API you wrote it yourself.