Cyrix was a U.S. company headquartered in Richardson (Texas ), which advanced microprocessors for PCs. Cyrix was founded in 1988 by former employees of Texas Instruments.

Cyrix was a so-called fabless company, so did not have its own manufacturing facilities. Instead, let behalf at Texas Instruments, SGS -Thomson and ST Microelectronics and IBM, then later finished at National Semiconductor and finally at TSMC. This fact meant that Cyrix processors were often sold from production partners under their name. In particular, the IBM versions of these processors were well known.

The first products of the company were math coprocessors for 8086 processors. 1992 was brought then with the Cx486SLC the first full-fledged x86 microprocessor on the market. Since Cyrix had access to no -licensing agreement with Intel, all processors have been developed completely self as opposed to AMD and were only compatible with the Intel processors. In view of its architecture, it often caused problems with motherboards and application software, which Cyrix earned a rather bad reputation.

  • 4.1 80486 ( Cyrix Cx486 family)
  • 4.2 5th generation
  • 4.3 6th generation


The aforementioned Cx486SLC appeared in June 1992 and was intended, together with the Cx486DLC for 80386 motherboards, but had features of the 80486 generation. Thus, relatively cheap PC systems were possible with these processors, as older components could be used. Nevertheless, the sales figures were rather modest mainly because of lower performance compared to Intel's i486 family.

In May 1993, Cyrix then brought to the Cx486S their first processor for 80486 motherboards on the market. This corresponded to the i486SX and thus did not have a math co- processor. This came as a surprise, since Cyrix until then had mainly built mathematical co-processors that are primarily due to the very high efficiency - was up to ten times faster than the Intel 387DX Cyrix 387 of the - well sold with full compatibility. In the course of 1993 we completed the range of 80486 processors with Cx486DX and the Cx486DX2 which the respective Intel counterparts ( i486DX and i486DX2 ) largely corresponded. However, the Cyrix processors were with other (higher) clock rates used, and sold much cheaper.

The hybrid processors Cx486SLC and DLC were in September or successor in the form of Cx486SRx ² and ² Cx486DRx. Both processors corresponded largely to their predecessors, but as the Cx486DX2 had an internal clock doubling, thus much higher clock speeds were possible.

Then in 1995 came with the Cx486DX4 another refresh of Cx486 family and with the Cyrix 5x86 a very interesting CPU on the market. The Cyrix 5x86 (codename M1sc ) was again a hybrid CPU, but this time for 80486 motherboards, but based already on the advanced design of the 6x86. The CPU was thus a perfect upgrade CPU for 486 motherboards, and it appeared to her many upgrade kits from third party companies such as Evergreen.

The already mentioned Cyrix 6x86 (codename M1 ), however, had been developed for the base 5 and so pin - compatible with the Intel Pentium. Note that the integer performance of the Intel Pentium 6x86 was so far superior that a CPU with only 133 MHz faster than a Pentium 166. Therefore, the so-called P Rating (PR ) was introduced so that the CPUs were comparable.

In response to the Intel Pentium MMX, the Intel Pentium II and AMD K6 (all with MMX technology ), presented on 30 May 1997 the Cyrix Cyrix 6x86MX (M2 ) before. This CPU was based in large part on the old Cyrix 6x86, but was equipped with a larger L1 cache, an improved branch prediction and a MMX -compatible technology ( EMMI ).

All in all a pretty good CPU that could show off thanks to the improvements in the integer range and in turn achieves higher performance than its competitors at the same clock frequency. For this reason, in turn, a P rating was used. Another change from the 6x86 was the use of much more flexible multipliers: x2, 5 was possible and thus a much greater range of clock frequencies.

Until then, it looked technically actually quite good for Cyrix: They had a competitive CPU, a relatively high market share and many patents. Financially, it was less good: It was losing money for years, the battle with Intel and AMD took a lot of money, and ultimately the AMD K6 had been able to win many supporters, which pushed the sales of the 6x86MX.

Then the acquisition by National Semiconductor was announced in November 1997. With NatSemi in the back, it was assumed that Cyrix in the future could offer competitive products, with the Cayenne / Gobi design a corresponding CPU was in development.

On April 15, 1998, came the first disappointment: Cyrix turned on that day before the Cyrix MII. However, this CPU was not new, but it was just a renamed 6x86MX. The first were the MII MII 300 and MII 333rd Surely these CPUs were not bad, but the architecture was already a year old and against the AMD K6 -2 and the Intel Pentium II could be so - esp. because of the low clock rates - do not exist. IBM did not make the fad of change of name by the way and sold the MII -300 and -333 continue as 6x86MX - PR300 and PR333 - 6x86MX.

Cyrix fell back, sales plummeted. Now it turned out that NatSemi was more interested in system-on -a- chip ( SoC ) in the form of MediaGX processors than desktop CPUs. This was disastrous for the development of a new desktop CPU. Mid-1999, then came the news that NatSemi Cyrix sold to VIA Technologies (Taiwan). As a first measure VIA announced the production of the MII CPUs to TSMC, and thanks to The - Shrinks to 0.18 microns, the clock rates increased slightly, and they brought yet the MII -366, MII 400 and MII 433 on the market.

In early 2000 a new CPU named Cyrix, VIA Cyrix III was finally presented again to the public. This CPU had been so long in development that she had received three different code names: Originally with the development under the name " Cayenne " was begun when Cyrix was still independent. After the merger with NatSemi the code name was changed to " Gobi ". But in the two years of belonging to NatSemi could not be completed, the CPU. Only after the takeover by VIA Technologies, the CPU under the code name "Joshua" was finished.

Due to the long development time could actually expect a mature product, but the VIA Cyrix III was only on paper a very interesting CPU for Socket 370 and disappointed in the first preliminary tests: instabilities, high heat, and very low clock rates associated with completely utopian P ratings ( as much too high ) meant that VIA Technologies, the Joshua design completely gave up and instead developed by Centaur Technology VIA Cyrix III Samuel as sold.


The CPU technology Cyrix was later used only in the Geode CPUs from National Semiconductor. The Geode SoCs based on the design of Cyrix MediaGX and were slightly improved by National Semiconductor. The SoC division was acquired by AMD in 2003. AMD offered the same product under the name Geode GX. 2005 was published with the Geode LX a further improved version of the old Cyrix MediaGX. The also offered by AMD Geode NX but based entirely on the architecture of the AMD Athlon XP.

On 24 October 2005, AMD has the x86 technology from Cyrix to the Chinese Ministry of Science and Technology (Chinese Ministry of Science and Technology - MOST), and licensed to the University of Beijing for the development of embedded and low-power x86 components.

Today, the Cyrix technology is no longer actively promoted by her current owners as a brand.

Math coprocessors

Cyrix 287

  • Cyrix 287XL ( )
  • Cyrix CX- 82S87

Cyrix 387

  • Cyrix CX- EMC87 or AutoMATH
  • Cyrix Cx87DLC
  • Cyrix 387DX
  • Cyrix 387SX
  • Cyrix 387SL


  • CyrixCX - 83D87
  • CyrixCX - 83S87
  • Cyrix 387DX


80486 ( Cyrix Cx486 family)

  • Cx486SLC
  • Cx486SRx ²
  • Cx486DLC
  • Cx486DRx ²
  • Cx486S
  • Cx486DX
  • Cx486DX2
  • Cx486DX4

5th generation

  • Cyrix 5x86
  • Cyrix 6x86
  • Cyrix MediaGX SoC

6th generation

  • Cyrix 6x86MX
  • Cyrix MII
  • VIA Cyrix III
  • Cyrix MediaGX SoC