Editing Pentium III (section)

==={{Anchor|Katmai}}Katmai===
[[File:Intel Pentium III Katmai.jpg|thumb|right|A Pentium III ''Katmai'' SECC2 cartridge with heatsink removed.]]
[[File:Intel@250nm@P6@Katmai@Pentium III@SL35D DSCx1 polysilicon microscope stitched@5x (38241648116).jpg|thumb|Katmai Die shot]]
The first Pentium III variant was the Katmai (Intel product code 80525). It was a further development of the [[Deschutes (microprocessor)|Deschutes]] Pentium II. The Pentium III saw an increase of 2 million transistors over the Pentium II. The differences were the addition of execution units and SSE instruction support, and an improved [[CPU cache|L1 cache]] controller{{citation needed|date=September 2017}} (the L2 cache controller was left unchanged, as it would be fully redesigned for Coppermine anyway), which were responsible for the minor performance improvements over the "Deschutes" Pentium IIs. It was first released at speeds of 450 and 500&nbsp;MHz on February 28, 1999. Two more versions were released: 550&nbsp;MHz on May 17, 1999 and 600&nbsp;MHz on August 2, 1999. On September 27, 1999, Intel released the 533B and 600B running at 533 & 600&nbsp;MHz respectively. The 'B' suffix indicated that it featured a 133&nbsp;MT/s FSB, instead of the 100&nbsp;MT/s FSB of prior models.

The Katmai contains 9.5 million transistors, not including the 512 Kbytes L2 cache (which adds 25 million transistors), and has dimensions of 12.3&nbsp;mm by 10.4&nbsp;mm (128&nbsp;mm<sup>2</sup>). It is fabricated in Intel's P856.5 process, a 250 nm complementary metal–oxide–semiconductor ([[CMOS]]) process with five levels of [[aluminum interconnect]].<ref name="MPR=1999-03-08">{{cite journal|url=http://docencia.ac.upc.edu/ETSETB/SEGPAR/microprocessors/pentium3%20(mpr).pdf|last=Diefendorff|first=Keith|author-link=Keith Diefendorff|date=March 8, 1999|title=Pentium III = Pentium II + SSE: Internet SSE Architecture Boosts Multimedia Performance|journal=[[Microprocessor Report]]|volume=13|issue=3|access-date=September 1, 2017}}</ref> The Katmai used the same slot-based design as the Pentium II but with the newer [[Slot 1]] Single Edge Contact Cartridge (SECC) 2 that allowed direct CPU core contact with the heat sink. There have been some early models of the Pentium&nbsp;III with 450 and 500&nbsp;MHz packaged in an older SECC cartridge intended for [[original equipment manufacturer]]s (OEMs).

A notable [[stepping level]] for enthusiasts was SL35D. This version of Katmai was officially rated for 450&nbsp;MHz, but often contained cache chips for the 600&nbsp;MHz model and thus usually can run at 600&nbsp;MHz.