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Re: x86 architecture concepts
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Yes.  The registers, instruction set, memory addressing method, and I/O
design make up the programmers' model.  That is one level of processor
architecture.  It has a major influence on the hardware design, but
doesn't totally determine it.  You noted different implementations
having different performance and power tradeoffs.

IBM exposed the separation when they defined the System 360 architecture
in the 1960s, then implemented several computer models using very
different hardware designs.  Microprogramming allowed them to implement
machines with a wide range of performance, yet executing the same
instruction set.

Today there is are many ways to implement a given programmers' model on
all but the bottom-end processors.  You might call this the hardware
architecture for the machine.

Thad


Re: x86 architecture concepts
*** rude top-posting fixed ***
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Please do NOT toppost.  It is rude and extremely annoying.

and a set of registers.  The register set has expanded since the
8086, but has not changed the fundamentals.  The registers tend to
be special purpose, such as source and destination index (si and
di), counter (cx), accumulator (ax), block pointer (bp), rather
than general registers.  AMD and Intel have much different
implemenations of the same basic architecture.  (Although AMD got
into the business as a licensed second source for the Intel CPUs,
but that ran out and they compete on their own now.)

--
Chuck F ( snipped-for-privacy@yahoo.com) ( snipped-for-privacy@worldnet.att.net)
   Available for consulting/temporary embedded and systems.
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Re: x86 architecture concepts

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http://www.x86.org /


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Partly, because it was designed by a company other than those that
designed ARM, PowerPC and Alpha.  Partly, because x86 existed way before
the said architectures.


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ARM:     http://www.arm.com
PowerPC: http://www.ibm.com
Alpha:   http://www.dec.com

(Some links might be obsolete)

HTH,
   Vadim

Re: x86 architecture concepts
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I'm not sure, see the PXA processor from Intel that use ARM
architecture........



Re: x86 architecture concepts

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Absolutely.  PXA is based on XScale (micro)architecture, which is in turn
"ARM Architecture 5TE", by ARM nomenclature.

Your original question was about x86, which is completely different can of
worms.  It all has started the day Intel decided to ..ermm.. "extend"
their i8080 processor and make it 16-bit.  The new i8086 processor had
inherited the odd registers functionality and names.  Subsequent family
members (286, 386, 486, 586 aka Pentium, 686 aka PentiumII) just added to
the mess.  Due to the numbering convention this whole line is referred to
as "x86".

As Intel produces Itanium (or do they still?), the "x86" get another name,
"IA32".  Itanium, for it's 64-bit nature, is named "IA64".

And now ask somebody about i8035 or i8051 :)


HTH,
   Vadim

Re: x86 architecture concepts
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OK.

You mean that the only way for non Intel processors (AMD's one, Crusoe,
Geode) to be called x86 is to have the same instruction set and main
registers as Intel's x86?

Wasn't there any patent on the Intel x86 instruction set that did not allow
any other company to build x86 processors?



Re: x86 architecture concepts

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Yes.  The proper term for the 32-bit group of the x86 family is
IA32.  If that's what you're talking about (rather than the 16
bit or 64 bit parts), you should say IA32.

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Other companies built x86 processors.

That pretty much answers your question about the existence of
_any_ X where X would not allow other companies to build x86
processors.

--
Grant Edwards                   grante             Yow!  Don't hit me!! I'm in
                                  at               the Twilight Zone!!!
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Re: x86 architecture concepts

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Yes.  If it looks like x86, walks like x86 and quacks like x86 - it is x86
:)  All competitors' (AMD etc.) processors can execute the binary code for
Intel's x86.  *How* they do it internally -- might be completely different.


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No, IMHO.


   Vadim

Re: x86 architecture concepts
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According to my own, dim, memory, history says that there were indeed
several licencing-related restrictions and patent portfolios involved.
AMD was granted licences back in the day (8086 and 8088, or maybe even
8085-vintage) when "second sources" had to be available before anyone
would buy a part. I don't think that they were the only ones to get
licences for that reason. IBM got licences in order to build (I think) the
386sx or some such. Transmeta and the originators of the Geode (wasn't
always National Semiconductor: they bought it from ?Cirix?) get to build
their chips because they use IBM's fab facilities, and therefore come
under IBM's licence agreements. Or so I've read.

Cheers,

--
Andrew


Re: x86 architecture concepts
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I believe there were copyrights asserted on the instruction
mnemnonics.  However they were licensed to AMD early on, along with
the dies etc. to build the earlier x86s.  That die license (for 2nd
sourceing) was pulled about the time of the 286 (or was it 386?)).
However I believe that process allowed the use of the mnemnonics
forever.

--
"If you want to post a followup via groups.google.com, don't use
 the broken "Reply" link at the bottom of the article.  Click on
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Re: x86 architecture concepts

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It was pulled when pentium (586) came out. AMD made 8086, 286, 386, 486
(intel design). When intel made pentium, AMD could not catch up, so AMD
made those 100MHz and 133MHz 486's. AMD's own design, 586, does not work
fast enough to compete with Intel Pentium. So AMD had to buy Nexgen
(founded by former employees from Intel), and made the new Nexgen processor
686. Thats when AMD started to catch up.

vax, 9000

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Re: x86 architecture concepts

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Intel tried, AMD sued claiming the agreement covered derivatives
and improvements ... for ever and ever and ever.  To a large
part the courts agreed.

Then AMD sued for the right to make 8087s, selling for $300 at
the time.  By the time AMD won the suit the 486 was out and the
issue was moot.  But boy did the lawyers and consultants rake it
in.

AMD used to be the premier second-source house.  But it turned
out Jerry Sanders was just a crook.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer:  Electronics; Informatics; Photonics.
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Re: x86 architecture concepts
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I have the original introduction by Morse the designer of the
8086. He is somewhat critical of his own design and Intels assembler,
too. I think the 8086 is a decent processor, and a feat of upwards
compatibility. But it really should have been the end of it.
Extending the lifetime of the processor from 16 bits to 20 bits
addressing, counting for 4 years in computer history, and there it
should have stopped.

 The real mess didn't start until the addition of protected mode.
Even so, some Unix clones (notably Coherent) show that there was
a way out.

But Microsoft killed the attempts of IBM to get out of the BIOS
morass (microchannel) and forced Intel to introduce the "virtual
real mode".

Even so Linux proves that if you ignore sufficient of its features
the Intel 386 is a decent processor. A great deal of the mess
in a Linux system has to do with the battle for the control of the
boot code waged by Microsoft (BIOS).

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8051 another dead-ugly processor ...
But I prefer them over the PIC's.

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--
--
Albert van der Horst,Oranjestr 8,3511 RA UTRECHT,THE NETHERLANDS
        One man-hour to invent,
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