Changes
CRTC
,/* HSYNC and VSYNC */
Bit0 of port B of the PPI is directly connected to the VSYNC pin of the CRTC.
=== Ghost VSYNC ===
On CRTC 2, if a VSYNC is triggered during an HSYNC, the CRTC produces a ghost VSYNC. The CRTC then counts the lines as if a VSYNC were taking place by preventing a new VSYNC from occurring, but without the VSYNC pin being enabled.
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