But still, internally we call it i586, because that's the way it is. so is Pentium MMX which I reckon is called i686.
> The name invoked the number five, but was completely trademarkable, unlike the number 586.
The original Pentium I believe introduced a second pipeline that required a compiler to optimize for it to achieve maximum performance.
AMD actually made successful CPUs based on Berkeley RISC, similar to SPARC (they used register windows). The AMD K5 had this RISC CPU at its core. AMD bought NexGen and improved their RISC design for the K6 then Athlon.
some say that they tried to add 486 with 100 and the result had some numbers after the comma, that's why they named it pentium (yes, i know about the FDIV bug)
Intel's marketing department threw a fit, they didn't want the Pentium 4 competing with their flagship Itanium. Bob Colwell was directly ordered to remove the 64-bit functionality.
Which he kind of did, kind of didn't. The functionally was still there, but fused off when Netburst shipped.
If it wasn't for AMD beating them to market with AMD64, Intel would have probably eventually allowed their engineers to enable the 64-bit extension. And when it did come time to add AMD64 support to the Pentium 4 (later Prescott and Cedar Mill models) the existing 64-bit support probably made for a good starting point.
Bob Colwell talks about this (and some of the x86 team vs Itanium team drama) in his quora answer and followup comments: https://www.quora.com/How-was-AMD-able-to-beat-Intel-in-deli...
December 1998 $85 Celeron 300A handily beating June 97 $594 Pentium 233 MMX, not to mention overclocked one matching 1998 $621-824 Pentium 2s.
January 2002 $120 Duron 1300/Celeron 1300 beating 2000 $1000 Athlon 1000/Pentium 3 1000-1133
June 2007 $40 Celeron 420 overclockable out of the box from stock 1.6 to 3.2GHz beat best $1000 CPUs of year 2005 (FX-57, P4 EE).
Same goes for Graphic chips starting around 1998/9.
But the time since 2020 feels much faster again. It's scary! But it's exciting.