O Plameras was once rumoured to have said: > Architecture wise, some changes from i386 to i586:
> 1. Native floating point in i586 (present in i486 but disabled, option > to install co-processor in i386) Actually, the FPU in the i486 is enabled on the 486DX series, but not on the 486SX series. This differs from the 386 SX/DX where the 386SX had a half-width external databus vs the full 32-bit wide databus on the 386DX, but neither 386SX nor 386DX had an inbuilt FPU. The Pentium saw major improvements to overall FPU performance. When it wasn't returning incorrect values that is. Of course, this is all pretty moot since you'd have to be pretty crazy to still be using a 486 (or older) class system. However, it is important to note that there are a few 'embedded'/low performance CPUs around that don't support the Time Stamp Counter - a feature which Pentium optimised kernels generally require. > 4. MMX instructions for multimedia. MMX was only introduced in the later Pentium MMX and Pentium II CPUs. After the introduction of MMX, the Pentium Pro (i686) was still available, and did not support MMX. The 'correct' method to test for MMX (and later extensions) is to check the output of the CPUID instruction. (Introduced in the late 486 families - guaranteed to be available on all Pentium class or newer systems however.) It is the CPUID instruction that the linux kernel uses to generate most of the information in /proc/cpuinfo on i386 systems. C. -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
