Vertical Video Line Offset Register
|Short Description||Offset numbering of raster lines in copper/interrupt/active register|
Since core 3.1.5 (new register):
Bits 7-0 form offset value 0..255, the offset is added to Copper, Video Line Interrupt and Active Video Line readings.
Normally the ULA's pixel row 0 aligns with vertical line count 0. With a non-zero offset, the ULA's pixel row 0 will align with the vertical line offset.
Since a change in offset takes effect when the ULA reaches row 0, the change can take up to one frame to occur.