From: utzoo!decvax!harpo!ihnp4!ixn5c!inuxc!pur-ee!iuvax!isrnix!greg
Newsgroups: net.unix-wizards
Title: SI info wanted
Article-I.D.: isrnix.172
Posted: Wed Nov 17 12:46:52 1982
Received: Thu Nov 18 08:45:31 1982

Here at isrnix, we are running a CDC 9766 300mb drive on our 11/44 with
a System Industries 6100 controller. There is a switch on the controller
that controls how data will be transfered during DMA operations (it's
called the DMA throttle count switch). There are 3 DMA options, one is
a burst rate of 2 words per NP request, one is a burst rate until SACK, 
whereby the controller will relinquish the bus to a higher priority reqest,
and the other option is "Throttle at microprogram control". My question
is (finally!): "What exactly does this mean?" The manual says nothing more
about microprogram control. Currently we are running at a burst rate of 2
words per NP request with no problems. Has anyone experimented with this
switch? We also have a (yeeech) RL11 controller that is badly buffered, so
I need to make sure the 6100 doesnt hog the bus, but I would like to get
the highest possible transfer rate out of the bugger.
		Any thoughts/experience on the matter?
		Thanks,
			Greg Travis
			decvax!pur-ee!isrnix!greg