== PSG Registers ==
The PSG has 16 read/writeable data registers, and a write-only index register. Both the index and data registers are accessed through PIO Port A, depending on the current setting of the BC1 and BDIR bits in [[PIO8255|PPI]] Port C. The four possible combinations are:
0=inactive 2=write data
1=read data 3=write index
The procedure to write data to a specific register is as follows: Write the register number to [[PIO8255|PPI]] Port A, set BC1/BDIR to Write Index - and back to Inactive. Now write the data to PIO Port A, set BC1/BDIR to Write Data - and back to Inactive.
* [[How to access the PSG via PPI]]