Xref: utzoo comp.sys.mac.hardware:12120 comp.sys.mac.programmer:25968
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!wuarchive!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!boingo.med.jhu.edu!haven.umd.edu!umbc3.umbc.edu!umbc4.umbc.edu!brian
From: brian@umbc4.umbc.edu (Brian Cuthie)
Newsgroups: comp.sys.mac.hardware,comp.sys.mac.programmer
Subject: Re: NuBus traffic
Message-ID: <1991Jun14.172938.10153@umbc3.umbc.edu>
Date: 14 Jun 91 17:29:38 GMT
References: <871@taniwha.UUCP> <1991Jun13.183543.12392@umbc3.umbc.edu> <14065@goofy.Apple.COM>
Sender: newspost@umbc3.umbc.edu (News  posting account)
Organization: Univ. of Maryland Baltimore County, Academic Computing Services
Lines: 35

In article <14065@goofy.Apple.COM> teener@apple.com (Michael Teener) writes:
>In article <1991Jun13.183543.12392@umbc3.umbc.edu> brian@umbc4.umbc.edu 
>(Brian Cuthie) writes:
>> Because
>> the NuBus is such a pig (at best, on a good day, ~30 Mbytes/sec, block mode)
>> there is a real bottleneck between the processor and the video ram.  Worse,
>> the NuBus is EXPENSIVE to design interfaces for.  Even the chipset that
>> TI has is $50 in quantity.
>
<stuff deleted>
>the controller is a joke.  Both parts are *too expensive*. If you look at 
>the NuBus cards done by Apple, Supermac, Radius, etc ... you will find 
>that all the interfaces are done using off-the-shelf transceivers and 
>semicustom controllers (slave boards without burst mode can get by with a 
>single PAL).  You pay for what you get ... a non-burst slave interface 
>will cost less than $10, a bursting master can cost $35 and require a 
>semicustom controller.

Yea, that's exactly the problem.  If you're not Apple, Supermac or Radius et al
then you have no chance of building an interface for a price that makes 
sense.  I looked into this a great deal about a year ago and concluded that
it is extremely expensive (compared to processor bus interfaces), in
both cost and parts count, to build a non-ASIC interface to the NuBus.
This is *exactly* the reason you don't see the range of interface boards
for the Mac that are available for the PC.  Nobody in the business is willing
to try to market a product who's retail price should be about $200 but has a 
TMC of $50 for the bus interface.

Of course, if you have the bucks to build an ASIC that does it for you, then
you're set.  Of course, does apple provide such a chip for it's developers?
No, instead they try to push this AROSE stuff on people.  Great idea, TOO
DAMNED EXPENSIVE!  Every board that apple has built using it retails for
>$1000. 

-brian