USB support - larger rom/ram support
Added 32-byte write support to ROM area! For MIST external sector buffer. TODO: Smarter method...
Added simple dma for faster sd card reading
Cleaned up ZPU into slightly more generic form, though still clearly atari core targetted. Added inital tb, though needs rom to verify more. MIST sector side removed, but should be possible with external changes. Now ZPU instead has lots of GPIO.
Current unmerged vhdl for my Atari800 core and start at merging them into one tree with a common core