NAME   rev ADDR type chip Description
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VBSTOP H 1CE   W    A    Vertical line for VBLANK stop
VBSRTR H 1CC   W    A    Vertical line for VBLANK start
		(V10-0 <- D10-0) Affects CSY pin if BLAKEN=1 and VSY pin
		if CSCBEN=1 (see BEAMCON0)