Changes
8255
,/* PPI Port B */
* Bit5 (/EXP) can be used by a expansion device to report it's presence. "1" = device connected, "0" = device not connected. This is not always used by all expansion devices. ''is it used by any expansions?'' [in the DDI-1 disc interface, /EXP connects to the ROM bank selection, bank 0 or bank 7]
* If port B is programmed as an output, you can make a fake vsync visible to the Gate-Array by writing 1 to bit 0. You can then turn it off by writing 0 to bit 0. It is fake in the sense that it is not generated by the CRTC as it normally is.
* For more info on LK1-LK4 (and further LKs) see [[LK Links]]
