Also, only CRTCs 1/2 have a dedicated C5 counter. On CRTCs 0/3/4, during Vertical Adjustment, C9 has to fullfil the VTAC role which means that it cannot fullfil its VLC role. This impacts address generation as R9 is not considered anymore.
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=== RA in IVM interlace mode ===
When IVM mode is activated, VLC continues to increment normally. However, RA is not identical to VLC anymore. Instead, VLC is considered shifted left by 1 bit, and bit0 represents the parity of the field (even/odd).
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