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9. CONFIGURING DMA
9.1
ALLOCATING DMA CHANNELS
The board implements the functionality of two 8237 DMA controllers. Eight DMA
channels are available.
According to Plug and Play standards, the system BIOS automatically allocates DMA
Channel 1 or 3 for the parallel port's ECP mode. Channel 2 is reserved for the floppy
controller and Channel 4 is used to cascade Channels 0 through 7 to the microprocessor.
DMA channels are assigned as follow:
DMA 0
DMA 1
DMA 2
DMA 3
DMA 4
DMA 5
DMA 6
DMA 7
NOTE
The DMA Channel for the Plug and Play Ethernet device is
automatically allocated by the system BIOS among those available
(Channel 3, 5, 6 or 7).
IRQ
&
Available
PnP available (ECP)
Floppy controller
PnP available (ECP or Ethernet)
Cascade controller # 1
PnP available (Ethernet)
PnP available (Ethernet)
PnP available (Ethernet)
9-1
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