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AMD and Intel Largely in Harmony on x86-64
SCOTTSDALE, Ariz., April
5, 2004 - An independent analysis by In-Stat/MDR's
(http://www.mdronline.com) Microprocessor Report
indicates that the 64-bit x86 architectures from
AMD and Intel are almost, but not quite, identical.
Near-100% software compatibility is possible, but
in some cases, programs written for one 64-bit architecture
may not run properly on the other 64-bit architecture.
Microprocessor Report compared
all the new instructions, modified instructions,
deleted instructions, and modifications to the register
files-including control registers, system registers,
and registers visible to application programs. Memory-addressing
schemes and many other architectural features, such
as data-addressing modes, context-switching behavior,
interrupt handling, and support for existing 16-
and 32-bit x86 execution modes were also compared.
In every case, Intel had patterned its 64-bit x86
architecture after AMD64 in almost every detail.
However, Microprocessor Report
discovered a few differences that even AMD and Intel
were unaware of. Some of these differences may be
resolved in future 64-bit x86 processors, or even
in future steppings of x86 processors already announced
or on the market. In other cases, software can easily
adapt to the differences by executing slightly different
code, after first probing the CPU to learn which
64-bit extensions it supports.
"We found nothing to contradict
Intel's promise that its 64-bit x86 processors will
run the 64-bit operating systems developed for AMD64,"
says Tom R. Halfhill, a Senior Editor with In-Stat/MDR's
Microprocessor Report. "At the same time, Intel's
reluctance to make a blanket guarantee about mutual
64-bit software compatibility is justified by the
minor differences we discovered. Of course, that's
always the case when Intel or AMD introduces new
x86 extensions-such as Intel's SSE3 media extensions,
which aren't yet supported by AMD."
Despite the differences, Intel
clearly derived its 64-bit architecture by reading
AMD's prerelease documentation for AMD64 and by
testing AMD64 processors. "Intel's reverse-engineering
of AMD64 marks a major turning point in the historical
relationship between the companies," says Halfhill.
"Although AMD has in the past introduced some
innovations to the x86 architecture-the 3DNow multimedia
extensions being a prime example-this is the first
time AMD has truly steered the direction of the
world's most important microprocessor architecture,
which Intel invented in 1978 and has closely guarded
for 26 years."
The article, "AMD and
Intel Harmonize on 64" can be found in the
March 29th edition of In-Stat/MDR's Microprocessor
Report, a subscription newsletter for makers and
users of high-performance microprocessors. To find
out more about Microprocessor Report, please visit:
www.mdronline.com.
Contact
Ton Halfhill, Senior Editor, Microprocessor
Report
Phone: 408.345.1635; Email: thalfhill@reedbusiness.com
Kirsten Skedd, Senior Marketing
Manager
Phone: 480.609.4534; Email: kskedd@reedbusiness.com
About
In-Stat/MDR
In-Stat/MDR
(http://www.instat.com) offers a broad range of
information resources and analytical assets to technology
vendors, service providers, technology professionals,
and market specialists worldwide. The company stands
alone in its ability to integrate both supply-side
and demand-side research methodologies into a single
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This capability relies on a unique ability to cover
the entire value chain from engineering-level technology,
through equipment, infrastructure, services and
end-users. In-Stat/MDR is part of the Reed Electronics
Group, a division of Reed Elsevier (www.reedelsevier.com),
a world-leading publisher and information provider.
With over 38,000 employees worldwide, Reed Elsevier
operates in the science & medical, legal, education
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on the Internet.
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