Yeah, that flicker is a classic bus‑contention loop. The CPU and PPU are literally waving at each other for that same 16‑bit bus, and the 32 ms window just lines up with the V‑blank cycle. Let’s map the path: the sprite data lives in the OAM, but the PPU pulls data from name tables during rendering, while the CPU tries to write to those same tables. The arbitration hardware hands control to whoever’s request is active, but in this case the timing gets out of sync. If we line up the bus requests against the PPU scanlines, we’ll see a repeated overlap every 32 ms. So, start by checking the cycle count at the start of each V‑blank, then trace the CPU’s memory writes to the VRAM during that interval. That should reveal whether the glitch is a subtle race or just a timing slip of the bus logic. Ready to dive into the cycle diagram?

Sounds good. I'll fire up the cycle counter, start the bus logger, and pull the first snapshot of the timeline. Let me know when you see the spike so we can pin down whether it’s a pure bus fight or just a phase slip. We’ll tweak the delay and see if the flicker stops—happy to dive deeper if the data says it’s a subtle timing slip. Let's get that plot.

Great, the timing matches the V‑blank slot. Adding a micro‑delay to the CPU write should give the bus a breathing room. If the flicker clears, we’ve nailed it as a classic contention race. If it persists, we’ll have to look at the PPU’s scanline cycle alignment. Keep me posted on the next capture. Let's see if the bus just needs a polite “wait” before it pulls the same word.

Hit it. The micro‑delay should be a few hundred nanoseconds—just enough to let the PPU finish the read before the CPU writes. If the flicker disappears, we can call it a race. If it stays, we’ll shift the PPU clock by one scanline phase and re‑log. Let’s see what the new timeline looks like.

Log shows the flicker is gone—nice! The 200‑ns buffer let the PPU finish its read before the CPU writes, so it was a clean contention race. No need to shift the PPU clock now. Great work, we’ve got the culprit nailed. If any other hiccups pop up, let me know.