Editing Cyrix 5x86 (section)

==Design==
The Cyrix 5x86 processor, codename "M1sc", was based on a scaled-down version of the "M1" core used in the Cyrix [[6x86]], which provided 80% of the performance for a 50% decrease in [[transistor]]s over the 6x86 design.{{citation needed|date=May 2020}} It had the [[32-bit]] memory bus of an ordinary 486 processor, but internally had much more in common with [[X86#Chronology|fifth-generation]] processors such as the Cyrix 6x86, the [[AMD K5]], and the Intel Pentium, and even the sixth-generation Intel [[Pentium Pro]].{{citation needed|date=May 2020}} The chip featured near-complete support for i486 instructions, but very limited support for Pentium instructions.{{citation needed|date=May 2020}} Some performance-enhancing features of the CPU were intentionally disabled due to potentially stability-threatening [[computer bug|bugs]] which were not fixed before release time (these features can be enabled with freely downloadable software utilities; see below).<ref>{{cite web |url= https://www.karlstechnology.com/blog/cyrix-5x86/ |title= Cyrix 5x86 CPU  |publisher= The PC Guide |last=Kozierok |first=Charles  |date= 16 March 2018 |access-date=May 29, 2019}}</ref>

The similarly named [[SGS-Thomson]] (STMicroelectronics) ST5x86 and [[International Business Machines|IBM]] 5x86C were licensed rebrandings of the Cyrix design (IBM and ST physically produced Cyrix's CPUs for them), marketed separately but identical for practical purposes, apart from the availability of a 75&nbsp;MHz edition which Cyrix did not bring to market, and slight differences in voltage requirements. The Cyrix 5x86 design, however, should not be confused with the similarly named [[Am5x86|AMD Am5x86]] which was essentially a clock-quadrupled 486 (not an all-new design like the Cyrix part) but which had broadly similar performance, used the same Socket 3, and was introduced at the end of the same year.

Cyrix's 5x86 was a very short-lived chip, having a market life of only six months. It is likely Cyrix could have continued to successfully sell processors based on Socket 3, but canned the 5x86 so that it would not compete with its then new 6x86 offerings.
{{multiple image |total_width= 320px
 | image1    = KL STMicroelectronics ST5x86.jpg
 | caption1  = STMicroelectronics ST5x86-100.
 | image2    = KL IBM 5x86C.jpg
 | caption2  = The IBM 5x86 with blue heatsink.
}}