Changes
/* Technical */
Port decoding appears to be:
bit 9 = wd1010 a2 bit 1 = wd1010 a1 bit 0 = wd1010 a0
bit 8 is 1 or 0, maybe it can't be either, but if it is set it could clash
with other i/o. The ports chosen here don't clash.
bit 10 = 0 bit 2 = 0
are the other bits checked for 1's?
