CRTC1.regStatus.VBLANK

[freemac]

I misunderstand the CRTC1.regStatus.VBLANK.
-it's not(VDISP)
-it's line 0 of not(VDISP)
-it has a constant length , double length in CRTC1
-it's the true flyback, after flying back at top left of screen the gun is ready but waiting the "go" signal.


For the moment, I turn this signal into '1' when VDISP has ended and for a length of 2 HSYNC, is it correct ?