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The C Users' Group Library 1994 August
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v_06_07
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v6n7024a.txt
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1989-09-28
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Table 9 - DMA chip command sequence for floppy data transfers
-------------------------------------------------------------
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.