=Technical information=
* Port &F988: read status 0 or select a page 0 register
* Port &F888: read/write to the selected page 0 register
* Port &F984: read status 1 or select a page 1 register
* Port &F884F888: read/write to the selected page 1 register
The SSG, the digidrums and the first 3 FM chans are accessed on register page 0. The last 3 FM chans are accessed on register page 1.