Changes
8255
,/* PPI Control */
* CAUTION: Writing to PIO Control Register (with Bit7 set), automatically resets PIO Ports A,B,C to 00h each!
* 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.
[[File:Intel 8255A - IO modes control word format.jpg]]
=== PPI Control with Bit7=0 ===
Bit 7 SF Must be "0" in this case
[[File:Intel 8255A - BSR Control Wordcontrol word format.pngjpg]]
== Programming Examples ==
