[rescue] DEFPA Programming Docs?

Dave McGuire mcguire at neurotica.com
Mon Jan 20 17:13:49 CST 2003

On Monday, January 20, 2003, at 04:05 PM, Jochen Kunz wrote:
> What does the QBus deliver? 3 MB/s?
> Well. Maybe the KA630 isn't able to saturate even the QBus.

   3.3MBps, compared to Unibus' 7MBps.  I believe most of the drop in 
speed from Unibus to Qbus comes from the fact tht the data and address 
lines are multiplexed on to the same set of lines in Qbus, so data and 
addresses can't be sent at the same time.  Remember Qbus was intended 
as a lower-cost alternative to the older Unibus.

> Uhh. 700a. Nice. I have only a /400. (/300 with /400 board set)
> Yes. The QBus in later VAXen is good for a bunch of serial cards, but
> that's it.


   I have a matched pair of /400s; I recently upgraded one of them to a 
/500.  I really like those machines.  I have a couple of /300s (two I 
think) as well as a 600a that lives with Brian Hechinger.  Those later 
4000-series machines are respectably fast.  I also like the fact that 
they're very quiet and pull surprisingly little power.

   You're running NetBSD on your /400, aren't you?


Dave McGuire           "Wear whatever you want...Just don't be surprised
St. Petersburg, FL        if you wind up with a blow-gun dart in your
                            prosthetic boobies."    -Kurt Huhn

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