>At 04:01 PM 2/24/96 -0600, Chuck Cranor wrote:
>        Not knowing much about hardware, that's what I figured.  What DMA
>would an Ethernet board have to do?

well, the "ie" chip uses DMA to transfer data between the network and
memory.    it also uses DMA to transfer "commands" between the host and
the chip.   the way it works is that the driver sets up some standard
hardware-specific data structures in memory [with ie_setupram()] and 
then loads/unloads commands and data from that area of memory.    to get 
the chip to "do something" there is a register (struct ieob [ie0], or 
struct ievme [ie1]) which has an "attention" bit you set.   when this bit 
gets set, the chip uses DMA to check out the control data structures to 
see what command you have issued it (e.g. "init chip", 
"transmit packet", etc...).

the reason this DMA shouldn't cause problems for the 4/110 is because
it happens all local to the "ie1" card (you are not doing any DMA over
the VME bus).

>>one thing to check is the px03 and px04 VME jumpers which should both
>>be "OUT" for the "ie1" card.
>        I haven't checked these yet, but according to the Sun Hardware FAQ,
>no changes should be req'd to the VME jumpers if adding this Ethernet board.

i would double check this.   the default state for these jumpers is
usually "IN" ....

chuck