1. The function of these I/O ports is dependant on the CRTC type
2. * The CRTC is not connected to the CPU's RD and WR pins, so the CRTC is not aware of the CPU bus I/O direction. Therefore, if you perform an IN instruction to the select or write functions, it will write data to the CRTC from the current data on the bus.
==Addressing==