Changes

Some CPC emulators use Port &FEFE to provide a method to identify a specific CPC emulator. CPC programs could use this ID to detect an emulator and change some of their behaviour (e.g. changing graphic effechts effects which will not work on an emulator or using special emulator-specific features). Reading from this port returns the Emulator-ID or &FF on the real CPC and on emulators which do not provide this feature.