Changes
CRTC
,/* MA buffering */
At the end of the display of the last raster line of each character line (ie. when HCC=R1 and VLC=R9), MA' captures the current value of MA.
CRTC 2 is an the exception: at the end of the display of the last raster line of the frame, MA' captures R12/R13 instead of MA. <br> === "Rupture For Dummies" bug ===
CRTC 1 has a bug that occurs when R5 is updated with a non-zero value on specific HCC and VLC values, but only when R5 was previously 0. This disrupts the normal VMA update process, causing the CRTC to load R12/R13 into MA at the beginning of every scanline, regardless of the VCC value.
But if R5 is set back to 0 before HCC reaches R0 on the last scanline of the character line (when VLC=R9), the bug won't trigger.
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