What is the monochrome mode in the NES?
Bit 0 of $2001 is funny. When it is set, the entire palette goes grayscale. However, it is not a simple grayscale mode. For one, there is no black value when the monochrome bit is set. In fact, what technically occurs is that when the monochrome bit is set, the 64-value palette in the NES is reduced to simply a 4-value palette. All palette entries from $01 to $0F are mirrored to entry $00; all entries from $11 to $1F are mirrored to $10; all entries from $21 to $2F are mirrored to $20; and finally, all entries from $31 to $3F are mirrored to $30. This is also shown to be true because if you set the monochrome bit and some of the colour emphasis bits, the display still gets skewed to the colour being emphasized. • What are bus conflicts? Bus conflicts are what occur when a game program writes to a memory mapper in order to change a bank of CHR graphics or PRG code. Memory mappers get switched by having the NES program write to some address in the ROM address space [$8000-$FFFF]; however
