== CRTC counter differences ==
=== MA reload buffering ===
On CRTCs 0/3/4, at At the beginning end of the first display of the last raster line of the frameeach character line (ie. when HCC=R1 and VLC=R9), MA and MA' are loaded with R12/R13. Otherwise, captures the current value of MA is loaded with MA'.
On CRTC 2, is the exception: at the beginning end of every raster line the display of the frame (including the first one), MA is loaded with MA'. On CRTC 1, at the beginning of every last raster line of the first character line of the frame (ie. when VCC=0), MA is loaded with ' captures R12/R13 instead of MA'. '''This is a major source of incompatibility if the programmer does not take care.''' In demos and games, to be compatible with all CRTCs, program R12/R13 only when VCC != 0. This will then take effect at the next CRTC frame start.
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=== MA buffering reload ===
At On CRTCs 0/3/4, at the end beginning of the display of the last first raster line of each character line (ie. when HCC=R1 and VLC=R9)the frame, MA and MA' captures the current value of are loaded with R12/R13. Otherwise, MAis loaded with MA'.
On CRTC 2 is the exception: , at the end beginning of the display every raster line of the last frame (including the first one), MA is loaded with MA'. On CRTC 1, at the beginning of every raster line of the first character line of the frame(ie. when VCC=0), MA' captures is loaded with R12/R13 instead of MA'. '''This is a major source of incompatibility if the programmer does not take care.''' In demos and games, to be compatible with all CRTCs, program R12/R13 only when VCC != 0. This will then take effect at the next CRTC frame start.
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