/* Aleste 520EX Serial Interface and Color Palette Swap */
PPI Port A data direction must be output,
Aleste ExtReg must enable access to 8253, and disable access to PSG
* Note: According to the Aleste schematic, clock input is 4MHZ (16MHZ/4), not and it uses a russian 8253 clone. Not sure if that is correct (...?) theoretically Theoretically the 8253 supportsonly max 2.6MHZ, and anything faster requires a 8254, not a 8253.
