Path: utzoo!attcan!uunet!samsung!munnari.oz.au!uhccux!ames!vsi1!wyse!mips!winchester!kck
From: kck@mips.COM (Ken Klingman)
Newsgroups: comp.arch
Subject: Re: Integer Multiply/Divide on Sparc
Message-ID: <34406@mips.mips.COM>
Date: 12 Jan 90 02:15:10 GMT
References: <18132@umn-cs.CS.UMN.EDU>
Sender: news@mips.COM
Lines: 30

From article <18132@umn-cs.CS.UMN.EDU>, by mike@umn-cs.CS.UMN.EDU (Mike Haertel):
> I don't see how ABI is related to "open systems."
> 
> Source level compatibility ought to be enough for anyone.  With the

Source level compatibility is not enough.  An applications developer
wants to minimize the number of ports and different copies of the 
same package that must be produced.  Most applications developers do
not distribute source and would like to only distribute one version
per architecture.  That's the purpose of an Application Binary
Interface: standardize the binary interface to a system so that an
application developer need only distribute one version per architectural
version of a system.

This means that if a processor supplier adds some whizzy new feature
or adds some hardware performance enhancement in an upward compatible
fashion, but which requires recompilation to take advantage of, then
the chip vendor is effectively creating a new architecture.  An application
developer has to weigh the cost of producing a new version of an application
for a new architecture.  If the new features or the improved performance
warrants it, then the developer will take advantage of it.

This doesn't stifle creativity, but it tends to require much more
substantial architectural improvements than just minor tweaks.


Ken Klingman				Mips Computer Systems
kck@mips.com				928 Arques Avenue
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