Which bit of the byte written to a mapper register is taken into account first. For example, if I have the code

lda #$81
sta $FFFF

does it write a 1 to the array and then clear it all, or does it clear the array and write a 1 to bit zero afterwords? If I wanted, say, register 3 to have a value of %00011011, could I do this?

lda #$9B
sta $FFFF
lsr a
sta $FFFF
lsr a
sta $FFFF
lsr a
sta $FFFF
lsr a
sta $FFFF

or would I have to do a fifth shift and start with the value of %1011011x in the accumulator? Any explanation would be greatly appreciated. God bless you all.

When using the MMC1, the reset bit will be used INSTEAD of the data.

Also, you generally only reset it ONCE, and then always write it exactly 5 times at once.

--
Quietust
P.S. If you don't get this note, let me know and I'll write you another.