257-260: Dummy nametable fetch. A12 is low
261-264: Sprite pattern fetch (1 of 8). A12 is high
265-268: Dummy nametable fetch. A12 is low
269-272: Sprite pattern fetch (2 of 8). A12 is high
My notes are a bit different... but from the wiki anyways.
/* Cycles 257-320: Sprite fetches (8 sprites total, 8 cycles per sprite)
* 0-3: Read the Y-coordinate(0), tile number(1), attributes(2), and X-coordinate(3)
of the selected sprite from secondary OAM.
* 4-7: Read the X-coordinate of the selected sprite from secondary OAM 4 times
(while the PPU fetches the sprite tile data).
* For the first empty sprite slot, this will consist of sprite #63's Y-coordinate followed by 3 $FF bytes;
for subsequent empty sprite slots, this will be four $FF bytes.
Is this incorrect?
I was describing the activity on the PPU's external video memory bus. You're describing the activity on the internal OAM bus. Both appear correct to me.