NAME   rev ADDR type chip Description
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DSKDATR 008 ER   P  Disk DMA  data read (early read dummy address)

	This register is the disk-DMA data buffer.It contains 2
	bytes of data that are either sent to (write) or received
	from (read) the disk. The DMA controller automatically
	transfers data to or from this register and RAM, and when
	the DMA data is finished (length=0) it causes a disk
	block interrupt. See interrupts below.