Changes
CRTC
,/* Interlace and Skew (R8) */
[[File:CRTC Interlace modes.png]]
On all CRTCs, in both interlace modes, an additional line is added (the 625th line) at the end of the frame.
On CRTCs 1/3/4, this line is added at the end of the even frame. On CRTCs 0/2, this line is added at the end of the odd frame.
==== Interlace sync mode (ISM) ====
On the even frame, the CRTC displays the lines for which VLC is even. On the odd frame, the CRTC displays the lines for which VLC is odd.
It is necessary to reprogram the CRTC as if we were building a frame of 624 lines. The 625th line is managed automatically by the CRTC.
CRTC 2 is the exception as it considers each character line to be a double character line.