Learning Assembly, #20

Today I finally started learning about horizontal positioning. It’s every bit the wild ride I anticipated and I wouldn’t have it any other way xD

Here’s kind of how it works: positioning things on the Atari involves timing with the CRT display because the CPU and display run in sync. To position things vertically, you just wait for the right scanline. To position things horizontally, you have to start drawing when the beam is in the exact right position by counting clock cycles. The beam is always zooming and each CPU instruction takes a certain amount of real world time. To position things horizontally means spending the perfect amount of CPU cycles so that the beam is in the right spot to start drawing.