The data will then be written into the register.
=== Reading from the selected PSG register===
To read data from the PSG, PPI Port A must be operating as input. (See the document on the 8255 to see how to do this)
set bit 7 to "0" and bit 6 to "1" of PPI Port C
read data from PPI Port A,
The register data is available at PPI Port A.
=== Notes ===