SUMMARY: SuperSPARC vs SuperSPARC+

From: Jim Warner (warner@cats.ucsc.edu)
Date: Thu Jan 27 1994 - 02:25:19 CST


In a white paper describing the SS1000 and SS2000 in May 1993 titled
"A Scalable Server Architecture for Desktop to Data Center", the
SMCC technical marketing department said:

   ...and the CPU modules are the same as those used in the
   SPARCstation 10 model 51 and model 512MP.

There are many things you could say about the quoted line. Some
would be less than complimentary. At minimum, it is incorrect.
The plan when that line was written was that all SuperSPARCs
would contain a working interface to both the Mbus and to the Xbus
used in the SS1000 and SS2000. Yields of chips with working Xbus
interfaces has not allowed SMCC to ship only the "good" chip.
When yields allow (soon, they hope), the Mbus-only version
of the processor module will become history.

It seems that all speeds of processor modules are or have been
produced with part numbers that segregate them according to whether
they have a working Xbus interface. Without a functional Xbus,
the modules will not fly in the SS1000/SS2000. The SuperSPARC+
however, can be used in the SS10 and MP6x0.

Part # Name Order # Compatibility
------ ------- ------- -------------
501-2352 SuperSPARC 1163A MBus only
501-2360 SuperSPARC+ 1166A Universal (MBus and XBus)

One respondant (rnf@spitfire.tbird.com) says that the "+" has
better floating point performance.

My Sun sales person responded to the same question by explaining
the order numbers. He also pointed out that users buying an SS1000
today but thinking of upgrading to the SS2000 can purchase the
1165A modules with 2 megabytes of cache. Only 1 megabyte of the
cache will be used, however, until the upgrade to the dual Xbus
SS2000.

In a message to this list posted on Monday, Eckard Rueggeberg
said in a summary that Sun has shipped some 40 MHz processor
modules without supercache that have different defect. These
modules cannot be used in a multiprocessor SS10. The "defect"
in the 501-2352 seems far less painful than Eckard's.



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