Per Bjornsson wrote: > Pentium = 586 obviously. I like to refer to it as the Pentium ISA. The "586" moniker can be marketing-based. > Also a 586: > "The ÉlanSC520 microcontroller combines a 32-bit, low-voltage Am5x86 > CPU with a complete set of integrated peripherals..." No. The AMD 5x86 is a 486 _ISA_. The name "586" is _marketing_. Understand that the AMD 5x86 _is_ the AMD 486 with some performance tweaks (FSB, speed, cache, etc...). It's a 486 _ISA_. The AMD 5x86 _pre-dates_ the K5. It was always debated if the K5 was Pentium or 486 ISA. It seemed thave some issues with some Pentium instructions. The K5 redesign, or those with more than a 120MHz "rating" -- wasn't actual speed, were based on the 2nd generation NexGen Nx586 with FPU. The original NexGen Nx586 was a 4-issue i386 if you can believe that! I believe these latter K5s were i486 ISA with most Pentium ISA compatibility. [ NexGen's RISC86 sub-ISA core is at the heart of all current AMD processors ] It actually wasn't until the AMD K6 that it was fully Pentium ISA compatible. Cyrix had the same issues. Not only was the Cyrix 5x86 also only a 486 ISA, but the 6x86 through P200+ (150MHz) was _still_ a 486 ISA. I don't think it was until the "L" version or the "M2" that Cyrix made it to full Pentium ISA compliance. > Basically I think that I'm more or less agreeing with you: Fedora > shouldn't dump old ISAs unless there is a real, tangible gain; moving > beyond 486 doesn't really seems to give us that. Where we differ is > that I think that ignoring the 386 by explicitly using NPTL is a good > idea and very much in line with the Fedora goals. If NPTL require an 486 ISA, then a 486 ISA should be the standard, I'll concede. There are various segmenting/table paging issues that I understand even the 386 MMU doesn't handle. -- Bryan J. Smith, E.I. -- b.j.smith@xxxxxxxx
