rwl++++ A2A6L - HDMA Table Address low byte
rwh++++ A2A6H - HDMA Table Address high byte
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At the beginning of the frame $4362/3 are copied into this register for
all active HDMA channels, and then this register is updated as the
table is read. Thus, if a game wishes to start HDMA mid-frame (or
change tables mid-frame), this register must be written. Writing this
register mid-frame changes the table address for the next scanline.
This register is not used for DMA.
This register is set to $FF on power on, and is unchanged on reset.