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Mickey's Safari in Letterland shaking
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Author:  Dwedit [ Sun Mar 19, 2017 9:42 am ]
Post subject:  Re: Mickey's Safari in Letterland shaking

Those are equivalent. Just that your notes for 0-3 are leaving out the dummy nametable fetch, but are including the sprite fetch.

Author:  tepples [ Sun Mar 19, 2017 1:17 pm ]
Post subject:  Re: Mickey's Safari in Letterland shaking

Zepper wrote:
tepples wrote:
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.
Code:
/* 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.

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