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Path: cantaloupe.srv.cs.cmu.edu!rochester!udel!gatech!howland.reston.ans.net!zaphod.mps.ohio-state.edu!saimiri.primate.wisc.edu!zazen!doug.cae.wisc.edu!carter
From: carter@cae.wisc.edu (Carter Gregory)
Subject: Re: PDS vs. Nubus (was Re: LC III NuBus Capable?)
Organization: U of Wisconsin-Madison College of Engineering
Date: 25 Apr 93 11:18:30 CDT
Message-ID: <1993Apr25.111830.16095@doug.cae.wisc.edu>
References: <1993Apr16.191259.1@fnalf.fnal.gov> <C5MqK0.F29@liverpool.ac.uk> <1qpc9g$4mr@bigboote.WPI.EDU>
Lines: 57

In article <1qpc9g$4mr@bigboote.WPI.EDU> bchase@bigwpi.WPI.EDU (Bret Chase) writes:
>In article <C5MqK0.F29@liverpool.ac.uk> wis@liverpool.ac.uk (Mr. W.I. Sellers) writes:
>>Bill Higgins-- Beam Jockey (higgins@fnalf.fnal.gov) wrote:
>>: In article <C5KzLs.KKB@dartvax.dartmouth.edu>, hades@coos.dartmouth.edu (Brian V. Hughes) writes:
>>: > mmiller@garnet.msen.com (Marvin Miller) writes:
>>: >>My friend recently purchased a LC III and he wants to know if there is
>>: >>such a demon called NuBus adapter for his PDS slot? 
>>
>>: > The LC family of Macs can only
>>: > use PDS cards. They are not able to use NuBus.
>>
>>: Ah, but why?  Can some technically-hip Macslinger tell us what the
>>: difference is between PDS and Nubus?  
>>
>>: Is it impossible to make a gadget that plugs into PDS and ends in a
>>: Nubus card cage?  At least, Marvin's friend has not been able to
>>: locate one and neither have I.  What is the fundamental reason for
>>: this?
>>
>>I think that there do exist NuBus expansion cages (I'm sure I've seen
>>them advertised occassionally), but I think that the main problem is that
>>they cost much more than the difference in price between say a LC and IIvx
>>so unless you need lots of NuBus slots its not worth the bother.
>>
>>(Of course, it may be that these extra boxes are so expensive because
>>no one buys them because they are so expensive...)
>>
>>NuBus technology isn't a special Apple Proprietry thing (I have this
>>sneaky feeling that it is licensed from Texas Instruments???) so there
>>is no problem building an expansion box.
>
>Apple uses the IEEE Nubus-90 standard for their 32 bit backplane bus.
>(I got this from a technote that I reada couple of weeks ago)

Well, almost NuBUS 90 anyway, comprehensive bus contention between processors
is not supported in the current Macintoshes, could be wrong?

However, I know for a fact from seeing the Cyclone Data Spec sheets myself,
don't ask, Macintosh Cyclone models will provide full implementation of the
NuBUS standard.

Very interesting possibilities indeed!

>
>>>>>>>>>>>other stuff deleted<<<<<<<<<
>
>Hope this helps,
>Bret Chase
>
>
>-- 
>internet:bchase@wpi.wpi.edu			Macintosh!
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-Greg
