In the CRTC Compendium, chapter 7.3 "Fake VSYNC", [[Longshot]] has also experimented with reversing the direction of PPI port B to output a VSYNC signal from the PPI to the Gate Array. This technique is not for the faint of heart!
As an exception, the Ghost VSYNC of CRTC 2 overpowers the PPI Fake VSYNC.
=== Subpixel vertical hardware scroll ===