Changes
CRTC
,/* VCC (C4) overflow */
On all CRTCs, if Vertical Total (R4) is updated with a value less than VCC:
* if this update was done when VCC < R4, then VCC overflows and will continue to count up to its maximum value (127) before looping back
* if this update was done when VCC = R4, the decision current character line was already made decided to switch to vertical adjustment mode and no be the last one of the current frame. No update to R4 will make the CRTC change its mind for the current frame
The only exception when VCC = R4 is for CRTC 1 with a value of 0, which will cause the VCC to overflow.
