Article View: comp.arch
Article #10933Re: Any new instructions in a i486?
From: Ed McClannahan
Date: Mon, 14 Dec 1992 20:51
Date: Mon, 14 Dec 1992 20:51
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zeke@fasttech.com (Bohdan Tashchuk) writes:
>>>NeXTStep is said to not run on the Cyrix 486 chips because "they are
>>>not real 486's". No one has come up with a reliable reason _why_ NeXT
>>>doesn't think they are "real 486's" or why NeXTStep won't run on them.
>>I don't have any real data, but I expect the problem is that the Cyrix
>>chip doesn't have a floating point unit. Next's own systems have all
>>had standard FPUs, and reviews of NeXTStep say that it won't run on a
>>486SX, only a DX.
>A 10/21/92 semi-official net posting on NextStep claims it runs on SXs:
> General Requirements:
> CPU - 486 based PC Compatible Computer. This includes 486SX, 486DX,
> 486DX/2. Future Intel Microprocessor designs in the x86 family will
> also be supported. ISA or EISA expansion bus. 486DX and 486DX/2's are
> recommended for better performance.
> Will NeXTSTEP 486 run on the Cyrix 486SLC?
> No. The Cyrix chip not a true 486.
>I asked for an explanation of "true 486" in comp.sys.intel. A Next person
>seemed to imply that Next didn't want to bother resolving the supervisor
>state differences between the chips. Nothing very convincing. I had a theory
>involving "arrogant propeller-heads", but the Next person didn't agree with it.
>My guess is that NextStep is sluggish enough that Next saw no reason to bother
>with the Cyrix parts, which are lower performance than Intel 486?Xs.
>I've also seen Intel apologists and employees repeat the "not a 486" claim in
>various groups. They've succeeded admirably in their primary goal, which is
>to sow Fear, Uncertainty, and Doubt as widely as they can. What I haven't seen
>yet is an explanation. I'll ask the question again here:
> Please tell me exactly WHY the Cyrix isn't a 486? What is it that
> Intel feels is the essence of a 486?
> Let me say a priori that a response of "made or licensed by Intel"
> isn't sufficient in and of itself.
The jist I got was that NeXTstep wants to maintain compatible File Systems
between 680X0 and X86 platforms. To do this, they needed to do a lot of
byte swapping on the X86 platforms. Since the 486 has a simple instruction
to do it while the 386 does not, NeXT just went with the 486. I think their
justification was that you needed the horsepower of the 486 to run NeXTstep
anyway - atleast when you only look at X86 processors from Intel! This
assumption (of only considering Intel's product line) may, indeed, be the
real culprit as I think the Cyrix ne-486 is quite capable of running NeXTstep
from a performance perspective.
Note: The above impressions come from a Bay Area Next Users Group (BANG)
meeting I attended several months ago where the manager in charge
of NeXTstep "486" gave a rather detailed talk on the product. I'm
sorry I can't remember his name - but I do know he drives a 928 (or
something similarly fast) with a licence plate reading "NEXT 486".
He joked all night about choosing the 486 (and later the "586")
because it is FFAASSTT - like his car, get it? BTW: I took this
"486" decision to be yet one more indicator that NeXT does not
target the mass market. They seem to have completely yielded the
so-called "low end" to Microsoft, et. al. and are focusing on
finding that niche between the Desktop PC and Technical Workstations.
While they are certainly having some short-term success in this
market, I think they are doomed! I'm reminded of a line from "Other
People's Money" in which DeVito is explaining the folly of a strategy
of "gaining market share in a shrinking market". The niche NeXT has
staked out sure looks to me like one of those "shrinking markets".
Ed "doom and gloom" McClanahan
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Newsgroups: comp.arch Path: arc1-ca.pugleaf.net!sparky!uunet!news!wrs.com!edm From: edm@wrs.com (Ed McClannahan) Subject: Re: Any new instructions in a i486? Message-ID: <edm.724366309@wrs.com> Sender: news@wrs.com (News Manager) Nntp-Posting-Host: chaos Organization: Wind River Systems, Inc. References: <WAYNE.92Dec11164422@backbone.uucp> <9212130000.AA05447@iecc.cambridge.ma.us> <1992Dec14.134109.3367@fasttech.com> Date: Mon, 14 Dec 1992 20:51:49 GMT Lines: 70