Table 9 - DMA chip command sequence for floppy data transfers
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The following series of outputs will set up the DMA chip for transferring
data to or from the floppy disk controller.  The DMA chip base address
is I/O address 0.  Note:  This description will set up only for
transfers on DMA channel 2 (the floppy channel).

Offset    Data      Explanation
------    ----      -----------
0x0C      0x00      Clears an internal flip-flop in the chip

0x0B      ?         output a 0x46 if reading the floppy, or a
                    0x4A if writing to the floppy (or formatting).

0x04      low byte of physical address

0x04      bits 8 thru 15 of physical address

0x81      bits 16 thru 19 of physical address
                    This is not part of the DMA chip.

0x05      low byte of (transfer count less 1)

0x05      high byte of (transfer count less 1)
                    The DMA chip requires n-1.

0x0A      0x02      Enables the transfer.