What are the colour emphasis bits?
This is almost the final frontier of NES emulation, as not many emulators handle these bits properly. The top 3 bits of $2001 are known as the “Colour Emphasis Bits” because each bit modifies the R, G, or B colour component of the NES’ display. The bits look like this in $2001: BGRxxxx. If you set one of these bits, the entire palette changes dynamically towards the colour component selected in the bits. If you set the Red bit, the entire palette seems much more “red”. However, since the NES does not work in RGB, what seems to be happening is that the hue of all the colours in the display are more influenced towards the hue that is being emphasized. Another thing to note is that if the Red bit is set, for example, the palette entries that have a large amount of cyan [red’s negative] in them are darkened considerably. You can combine each of the emphasis bits as well. Setting both the R and G bits emphasizes the yellow in the palette, and so on. However, when any two bits are set, the e
