FDDI, was: Re: [rescue] u2 drive trays

Dave McGuire mcguire at neurotica.com
Tue Aug 19 12:48:36 CDT 2003

On Tuesday, August 19, 2003, at 01:34 PM, Jonathan C. Patschke wrote:
>> the defpa.* bus_dma changes, were, according to the netbsd diffs
>> quite straightforward, if i interpret it right.
>> the pqd.* changes are a magnitude larger
> What is pdq, anyway?  Is that the actual controller chip on the DEFxA?

   PDQ is the name of DEC's general FDDI interface architecture, which 
most of their FDDI controllers use.  I don't know much about it, but I 
do know there's an 68K on there...serious smarts.  It's also nice in 
that it implements SMT on the board, which some other controllers 
don't.  Probably because of the aforementioned smarts. :)

   DEC's PDQ-based FDDI controllers are:

   DEFPZ (Mezzanine PCI)
   DEFTA (TurboChannel)
   DEFQA (Qbus...which is slower than FDDI!)
   DEFAA (FutureBus)


Dave McGuire                 "You don't have Vaseline in Canada?"
St. Petersburg, FL                     -Bill Bradford

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