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From: tve@alice.UUCP
Newsgroups: comp.arch
Subject: Re: SPARC
Message-ID: <7456@alice.UUCP>
Date: Tue, 17-Nov-87 23:39:01 EST
Article-I.D.: alice.7456
Posted: Tue Nov 17 23:39:01 1987
Date-Received: Sat, 21-Nov-87 06:46:27 EST
Organization: AT&T Bell Laboratories, Murray Hill NJ
Lines: 43

1) SPARC has nothing to do with CRISP. SPARC essentially is
   Berkeley RISC modified and extended to suit the "real" world.

2) The only SPARC implementation available today  is the Fujitsu
   gate array (details have been posted). I have the data sheet,
   the bus interface is *horrible* unless you want to use the
   chip *exactly* as Sun does. Future versions by Fujitsu may
   be different (rumor).

3) The performance of SPARC implementations does *NOT* necessarily
   scale with clock rate! The Fujitsu gate array does LOADs in
   2 cycles (I-fetch, data-read) but STOREs in 3 cycles (I-fetch,
   i-don't-know-what, write-data). The data sheet doesn't say anything
   about that, but the Fujitsu rep. explained it. It has to do with
   the funny bus interface. I forgot the exact reason.
   All this to say, that another *implementation* of the SPARC
   *architecture* may use a different number of cycles, more
   busses or god knows what.

4) There is no way the Fujitsu SPARC chip can emulate 68020 code
   at 7MIPS (whatever that means). I think the confusion arises
   from the "source code compatibility" between Sun-3 (68020) and
   Sun-4 (SPARC) claimed by Sun. All that means, is that source code
   used on Sun-3 can be compiled for Sun-4 "unaltered".

5) The Fujitsu SPARC chip number is MB86900. There is a floating
   point controller to interface the SPARC cpu with Weitek 1164 and 1165
   chips. It's number: MB86910.

6) Flame ...
   Question: how many pins do you think the SPARC cpu has?
   Answer: 256!
   Question: how big do you think the package is?
   Answer: 2 inches on a side!
   Question: is this a joke?
   Answer: No!

Thorsten von Eicken
...!research!tve
tve@research.uucp

PS: Please correct if I mistated anything. I'm not trying to make the SPARC
    look bad ... nor good ... nor ...