This pair of registers contains the 20-bit address
        of blitter source (x=A,B,C) or destination (x=D)
        DMA data. Thia pointer must be preloaded with the
        starting address of the data to be processed by
        the blitter. After the blitter is finished, it
        will contain the last data address (plus increment
        and modulo).

LINE DRAW BLTAPTL is used as an accumulator LINE DRAW register and must be preloaded with LINE DRAW the starting value of (2Y-X) where LINE DRAW Y/X is the line slope. BLTCPT and LINE DRAW BLTDPT (both H and L) must be LINE DRAW preloaded with the starting address LINE DRAW of the line.
SEE ALSO: Blitter programming
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