End horiz blank        index 03h  CRTC  protected

Layout  b7     CR   Compatible read
        b6-b5  DES  Display enable skew
        b4-b0  EHB  End horizontal blanking

- Compatible read (bit 7)
        Enables or disables access to the Vertical retrace start and
        the Vertical retrace end registers.

        0 : Disable access to these registers.
        1 : Enable access to these registers.

- Display enable skew (bits 6-5)
        The number of character clocks to skew the position of the
        horizontal timing to achive proper synchronization. The
        two-bit binary value in this register represents the number of
        character clocks used to delay the timing.

- End horizontal blanking (bits 4-0)
        Determines the end of the horizontal blanking period. A sixth
        bit is found in the EHB field of the End horiz retrace
        register.