The only exception when VCC = R4 is for CRTC 1 with a value of 0, which will cause the VCC to overflow.
<br>
=== Vertical Adjustment mode ===
On CRTCs 0/1/2, this mode increments C4 and so C4 goes beyond R4.
On CRTCs 3/4, this mode does not increment C4 and so C4 stays equal to R4.
<br>