* On CRTCs 0/1/2, if a Write Only register is read from, "0" is returned. The register accessing scheme on CRTCs 3/4 makes it impossible to happen.
* CRTC types 3 and 4 are identical in every way, except for the unlocking mechanism, split-screen, hardware soft scroll and 8-bit printer port functionalities specific to the ASIC.
* See the document "Extra CPC Plus Hardware Information" for more details.