[net.lan] DEUNA & 4.2, Ethernet controller performance

dmmartindale@watcgl.UUCP (Dave Martindale) (03/29/84)

Yes, DEUNAs work well under 4.2 once you get a driver from somewhere.
We are running one here which is based on one written by Lou Salkind
at NYU.  My only complaint about the DEUNA is that it takes 16 amps
of +5V current, which is a very substantial chunk of the power available
in a single Unibus backplane in a BA11K box.

A new subject:  Has anyone measured actual DMA transfer rates on the
existing controllers?  It seems that the DEUNA transfers data from
its own memory to the VAX at about 4 microseconds per word, while
transferring data in the other direction at about 10 microseconds
per word (if I remember the two figures correctly).  It issues a
new NPR for each cycle, rather than holding the bus for more than one
cycle.  How do other controllers compare in transfer rate and intelligence
of using the bus?