Path: utzoo!utgpu!watmath!clyde!att!rutgers!tut.cis.ohio-state.edu!cwjcc!gatech!purdue!decwrl!ucbvax!hplabs!hpda!hpcuhb!hpesoc1!nicholso
From: nicholso@hpesoc1.HP.COM (Ron Nicholson)
Newsgroups: comp.arch
Subject: Why no RISC clones?
Message-ID: <5030006@hpesoc1.HP.COM>
Date: 29 Nov 88 03:26:51 GMT
Organization: Hewlett Packard, Cupertino
Lines: 34

What I don't understand is this: how do RISC designers protect their
investment.  A large part of the investment seems to be in deciding what
not to implement.  This becomes public when the instruction set manual is
published.

There is a big business in 370 compatibles.  Zilog got a big piece of the
micro market by cloning the 8080 instruction set.  All they had to change
was the instruction set mnemonics to get around the Intel copyright.

RISC processors have a lower design complexity than CISC processors
in the same performance range, and they are architected to be
independent of any particular implementation or technology.  This should
make them much easier to clone.

So what's the deal.  Is the instruction set a trade secret?  Can some
of the whiz-bang instructions only be done well by an IC layout which
is copyrighted?  Can an instruction be patented completely independently
of how it is implemented?  Is, perhaps, the collection of instructions
patented?  Maybe the architecture only works well with a compiler that is
very difficult to implement.  But does this make a difference in the
shrink-wrap ABI type market? 

Maybe an ASCII dump of common instruction sequences spell "Copyright
19XX Acme-RISC Co." or the register set comes up with that message after
a reset. 

If the instruction set is protected by patent or copyright, does that
mean that a software company that writes an instruction set simulator
is infringing?  How about if that simulator is implemented in microcode
or special hardware?

----
Ron Nicholson  - Hewlett Packard  - Cupertino, CA
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