One problem with the Atari 400/800 computers is that they have the ability to use any part of the 64k address space as frame buffer. You might ran zero page on

One problem with the Atari 400/800 computers is that they have the ability to use any part of the 64k address space as frame buffer. You might ran zero page on the FPGA and any ROM from a cartridge to get some performance boost though.