At Sat, 16 Jul 2011 22:31:51 -0700 CentOS mailing list <centos@xxxxxxxxxx> wrote:
>
> On 07/16/11 7:50 PM, david wrote:
> > If the I386 (or i686, never could figure out why the name change)
>
> I386 was the original 386 CPU, which ran at speeds from 16 to 33Mhz
> i486 includes a few additional instructions on the 486 processor, and
> IIRC, ran at speeds from 25 to 100Mhz
i486's included the FPU on-chip -- i386 either had a separate FPU chip
or used a kernel-supplied software FPU emulator (yes, 0.xx and 1.xx
kernels had the option of a software floating point math support).
> i586 is the original pentium, at 60, 66, 90, 100 up to about 133Mhz
AMD made K6's up to 500mhz -- i586 processors
> i686 is the pentium pro and pentium-II, -III, -IV and everything newer.
>
> i686 added a few minor new instructions but also has additional memory
> management functionality missing from the earlier versions.
>
> its just gotten silly to try and keep backwards support for the early
> versions of the CPUs that have been obsolete for so long.
>
> really, we should have compiler targets for optimizing on the P4
> 'netburst' CPUs and another for the core processors as they are all
> pipelined differently. as it turns out, however, the core 2 and core
> I3/5/7 do pretty well with pentium-II and -III style optimization
> strategies, as well as, of course, the x86_64 support.
>
>
--
Robert Heller -- 978-544-6933 / heller@xxxxxxxxxxxx
Deepwoods Software -- http://www.deepsoft.com/
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