Changes
8255
,/* PPI Control */
== PPI Control ==
This register has two different functions depending on bit7 of the data written to this register. === PPI Control with Bit7=1 ===If Bit 7 is "1" then the other bits will initialize Port A-B as Input or Output:
Bit 0 IO-Cl Direction for Port C, lower bits (always 0=Output in CPC)
* In the CPC only Bit 4 is of interest, all other bits are always having the same value. In order to write to the PSG sound registers, a value of 82h must be written to this register. In order to read from the keyboard (through PSG register 0Eh), a value of 92h must be written to this register.
=== PPI Control with Bit7=0 ===
Otherwise, if Bit 7 is "0" then the register is used to set or clear a single bit in Port C:
