They very much are synced up, since the PPU needs to generate the video signal directly: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Picture_Processing_Unit" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Picture_Processing_Unit</a><p>I&#x27;m not familiar with the NES in particular, but typically the software is synced with the video signal via hardware interrupts.