Changes
/* I/O Map and NMI Overview */
Port A10 A9 A8 A5 A3 A2 A1 A0 RW Expl.
FXDX 0 X X 0 X X X X The board selected.
F8DX 0 0 0 0 r r r r RW [[DMA Controller 8237]]
rrrr is reg number
D[7..0] Data
