[OFFTOPIC] Re: [?] Why should Distros be called as i386 for a 32-bit PC, and as amd64 for a 64-bit PC, when Intel Core PCs are also 64bit systems
> IA64 (Itanium) was completely incompatible with the installed i386 base.
> The first CPUs had a (very slow) compatibility layer, assisted by
> software, so you could run your "legacy" 16bit/32bit applications.
The original plan/claims was that the support for legacy i386
application would be "just as fast". This never materialized
(unsurprisingly: it's easy to make a CPU that can run efficiency several
slightly different instruction sets (ISA), like your average amd64 CPU which
can run applications using the amd64 ISA, the i386 ISA, the 80286 ISA
or the 8086 ISA, more or less; but it's much harder to make a CPU that
can run efficiently very different ISAs).
> Also the CPU was designed so that many complexities where delegated into
> the compiler to create the most optimal code but the compilers at the
> time where not up to the task, greatly hampering the new architecture.
More specifically, it depended on solving problems against which
compiler writers had banged their heads for several decades already (and
it is still on going). Worse: it was based on "old new ideas", IOW it
as trying to solve the problems that were already started to disappear
but was set o bump into new problems that were already starting
to appear.
The name Itanic came from the fact that it seemed likely (even quite
early on, meaning a long time before the name "Itanium" was announced)
to several (most?) knowledgeable CPU designers to lead to a monumental
failure ;-)
> Note: when IA64 was designed (starting in 1994 at HP) we where nowhere
> near the limits of the 32bit i386 architecture with RAM and frequency,
> so it made sense, somewhat.
Indeed. Also, they wanted to move away from the i386 instruction set so
as not to be bothered by pre-existing licensing agreements with AMD, and
thus making sure there'd be no competing implementation. The IA64
architecture was quite complex, and there are reasons to believe that
complexity was seen as a virtue (makes it easier to get more patents and
keep competitors out).
> But years passed and the i386 architecture got better and better,
> including stuff like MMX, SSE and AVX was incorporated, IA64 couldn't
> really keep up.
The IA64 architecture was a resounding success in one area tho: it
killed most of the competition that was coming from "above" (at least
DEC's Alpha, SGI's MIPS, HP's PA, and it likely sped up the demise of
Sun's SPARC, I don't think it had much impact on POWER or PowerPC, OTOH)
and thus helped open up the server (and supercomputer) market for Intel
(and AMD).
> Dnd when AMD then presented their AMD64 architecture that could run
> legacy 8bit/16bit/32bit code as fast as the new code, allowing for a
> smooth transition, the nickname "Itanic" for IA64 became true: It had
> been dead on arrival.
To make matters worse, the IA64 arrived very late to the market (IIRC
something like 3 years later than planned).
Stefan
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