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Cyrix Corporation
FateMerged & Dissolved
Successorsold to National Semiconductor (later sold to VIA Technologies), assets sold to Advanced Micro Devices
FounderJerry Rogers, Tom Brightman[1]
DefunctNovember 11, 1997
HeadquartersRichardson, TX, USA
Number of employees
approx. 300

Cyrix Corporation was a microprocessor developer that was founded in 1988 in Richardson, Texas, as a specialist supplier of math coprocessors for 286 and 386 microprocessors. The company was founded by Tom Brightman and Jerry Rogers. Cyrix founder, President and CEO Jerry Rogers, aggressively recruited engineers and pushed them, eventually assembling a small but efficient design team of 30 people.

Cyrix merged with National Semiconductor on 11 November 1997.


Cyrix FasMathcoprocessors

Cyrix FasMath

The first Cyrix product for the personal computer market was a x87 compatible FPU coprocessor. The Cyrix FasMath 83D87 and 83S87 were introduced in 1989. The FasMath provided up to 50% more performance than the Intel 80387. Cyrix FasMath 82S87, a 80287-compatible chip, was developed from the Cyrix 83D87 and has been available since 1991.

Cyrix Cx486DRx² Microprocessor.



Cyrix would later release the Cyrix 486SRX2 and 486DRX2, which were essentially clock-doubled versions of the SLC and DLC, marketed exclusively to consumers as 386-to-486 upgrades. Unlike the SLC/DLC, these chips contained internal cache coherency circuitry which made the chips compatible with older 386 motherboards that did not have extra circuitry or BIOS routines to keep the cache current.

Eventually, Cyrix was able to release the Cyrix Cx486S and later Cyrix Cx486DX that was pin-compatible with its Intel 486 counterparts. However, the chips were later to market than AMD's 486s and benchmarked slightly slower than AMD and Intel counterparts, which relegated them to the budget and upgrade market. While AMD had been able to sell some of its 486s to large OEMs, notably Acer and Compaq, Cyrix had not. The Cyrix chips did gain some following with upgraders, as their 50-, 66-, and 80 MHz 486 CPUs ran at 5 V, rather than the 3.3 V used by AMD, making the Cyrix chips usable as upgrades in early 486 motherboards.

Cyrix 5x86

In 1995, with its Pentium clone not yet ready to ship, Cyrix repeated its own history and released the Cyrix Cx5x86 (M1sc), which plugged into a 3.3V 486 socket, ran at 80, 100, 120, or 133 MHz, and yielded performance comparable to that of a Pentium running at 75 MHz. Cyrix 5x86 (M1sc) was a cost reduced version of the flagship 6x86 (M1). Like Intel's 486 Pentium Overdrive, the Cyrix 5x86 was 64-bit internally with a 32-bit external data bus. While AMD's Am5x86 was little more than a clock-quadrupled 486 with a new name, Cyrix's 5x86 implemented some Pentium-like features.

Cyrix 6x86-P166.

Cyrix 6x86

Later in 1995, Cyrix released its best-known chip, the Cyrix 6x86 (M1). This processor continued the Cyrix tradition of making faster replacements for Intel designed sockets. However, the 6x86 was the star performer in the range, giving a claimed performance boost over the Intel "equivalent". 6x86 processors were given names such as P166+ indicating a performance better than a Pentium 166 MHz processor. In fact, the 6x86 processor was clocked at a significantly lower speed than the Pentium counterpart it outperformed. Initially, Cyrix tried to charge a premium for the Cyrix-claimed extra performance, but the 6x86's math coprocessor was not as fast as that in the Intel Pentium. The main difference was not one of actual computing performance on the coprocessor, but a lack of instruction pipelining. Due to the increasing popularity of first-person 3D games, Cyrix was forced to lower its prices. While the 6x86 quickly gained a following among computer enthusiasts and independent computer shops, unlike AMD, its chips had yet to be used by a major OEM customer. The game in question causing most problems for performance was id Software's Quake. Unlike previous 3D games, Quake used the pipelined Pentium FPU to do perspective correction calculations in the background while texture mapping, effectively doing two tasks at once. This would not have been a big problem for the 6x86 if, by that time, Quake had a fallback to do perspective correction without the FPU as in, for example, the game Descent. However, id Software chose not to include this. Quake also lacked the option to disable perspective correction, thus eliminating that potential speed boost for FPU-weak CPUs. This potential speed boost would have benefited not just Cyrix's users, but also users of AMD's K5 and especially of the 486. Quake's optimization for the Pentium went beyond FPU usage and catered to a number of other architectural quirks specific to the Pentium, further hindering performance of other CPUs even outside FPU operations. This bias in favor of the Pentium served to boost the popularity of Intel's Pentium CPUs amongst the computer game community.

Cyrix 6x86L and 6x86MX

The later 6x86L was a revised 6x86 that consumed less power, and the 6x86MX (M2) added MMX instructions and a larger L1 cache. The Cyrix MII, based on the 6x86MX design, was little more than a name change intended to help the chip compete better with the Pentium II.

Cyrix MediaGX

Cyrix MediaGX

In 1996, Cyrix released the MediaGX CPU, which integrated all of the major discrete components of a PC, including sound and video, onto one chip. Initially based on the old 5x86 technology and running at 120 or 133 MHz, its performance was widely criticized but its low price made it successful. The MediaGX led to Cyrix's first big win, with Compaq using it in its lowest-priced Presario 2100 and 2200 computers. This led to further MediaGX sales to Packard Bell and also seemed to give Cyrix legitimacy, with 6x86 sales to both Packard Bell and eMachines following.


Cyrix Media GXi, Jedi and Gobi 'Cayenne'

Cyrix developed the 'Cayenne' core as an evolution of the 6x86MX/MII processor, with dual issue FPU, support for 3DNow! instructions and a 256K 8-way associative on-die L2 cache. This core was intended to be used in multiple products, including a successor to the MediaGX chip, a product codenamed 'Jedi' which was to be a Socket 7 compatible processor which was later cancelled in favour of a Socket 370 compatible processor codenamed 'Gobi'.


Cyrix M3 'Jalapeno'

This was a completely new core with a dual issue FPU, register renaming and out-of-order execution based on an 11-stage pipeline and 8-way associative, 8-way interleaved fully pipelined 256K L2 cache operating at core frequency.

Jalapeño's new floating point unit had dual independent FPU/MMX units and included both a fully pipelined, independent x87 adder and x87 multiplier. The Jalapeño design facilitated close integration between the core and the advanced 3D graphics engine, which was one of the first graphics subsystems to utilize a dual-issue FPU. The dual FPUs supported execution of both MMX and 3DNow! instructions.

Jalepeno had an on-die memory controller based on RAMBUS technology capable of 3.2GB/s to reduce memory latency and an integrated on-board 3D graphics which purportedly could process up to 3 million polygons per second and 266 million pixels per second based on a 233Mhz clock. The on-die graphics had access to the L2 cache of the CPU to store textures. The design's initial clock speed target was 600-800Mhz with headroom to scale to 1Ghz and beyond. It was due to begin production in Q4 1999 and launch in the year 2000 on a 0.18-micron process with a die size of 110-120 sq. mm.[3][4]

It's unclear how advanced development on this core was when Cyrix was acquired by VIA and the project discontinued.

PR system



Although AMD used the PR rating in its early K5 chips, it soon abandoned the PR rating with the introduction of the K6. However, it would use a similar concept in marketing its later CPUs, starting again with the Athlon XP.

Manufacturing partners

6x86MX under the IBM name

Cyrix had always been a fabless company: Cyrix designed and sold their own chips, but contracted the actual semiconductor manufacturing to an outside foundry. In the early days, Cyrix mostly used Texas Instruments production facilities and SGS Thomson (now STMicroelectronics). In 1994, following a series of disagreements with Texas Instruments, and production difficulties at SGS Thomson, Cyrix turned to IBM Microelectronics, whose production technology rivaled that of Intel.


Legal troubles

Unlike AMD, Cyrix had never manufactured or sold Intel designs under a negotiated license. Cyrix's designs were the result of meticulous in-house reverse engineering and often made significant advances in the technology while still being socket compatible with Intel's products. In Cyrix's first product, the 8087 math co-processor, Cyrix used hardware math multipliers rather than the CORDIC algorithm, which allowed the chip to be faster and more accurate than Intel's co-processor. Thus, while AMD's 386s and even 486s had some Intel-written microcode software, Cyrix's designs were completely independent. Focused on removing potential competitors, Intel spent many years in legal battles with Cyrix, consuming Cyrix financial resources, claiming that the Cyrix 486 violated Intel's patents, when in reality the design was proven independent. {Rulings from federal court in Sherman, Texas and Federal Circuit Court of Appeals in Washington DC.}

Intel lost the Cyrix case, which included multiple lawsuits in both federal and state courts in Texas. Some of the matters were settled out of court and some of the matters were settled by the Court. In the end after all appeals, the courts ruled that Cyrix had the right to produce their own x86 designs in any foundry that held an Intel license. Cyrix was found to never have infringed any patent held by Intel. Intel feared having to face the antitrust claims made by Cyrix, so Intel paid Cyrix $12 million to settle the antitrust claims right before a federal jury in Sherman, Texas was to hear and rule on the antitrust claims. As a part of the settlement of the antitrust claims against Intel, Cyrix also received a license to some of the patents that Intel had asserted that Cyrix infringed. Cyrix was free to have their products manufactured by any manufacturer that had a cross license with Intel, which included SGS Thomson, IBM and others. {Rulings from federal court in Sherman, Texas and Federal Circuit Court of Appeals in Washington DC.}

The follow-on 1997 Cyrix-Intel litigation was the reverse: instead of Intel claiming that Cyrix 486 chips violated their patents, now Cyrix claimed that Intel's Pentium Pro and Pentium II violated Cyrix patents--in particular, power management and register renaming techniques. The case was expected to drag on for years but was settled quite promptly, by another mutual cross-license agreement. Intel and Cyrix now had full and free access to each other's patents. The settlement didn't say whether the Pentium Pro violated Cyrix patents or not; it simply allows Intel to carry on making products under a license from Cyrix.

Merger with National Semiconductor




Cyrix MII 433GP front
Cyrix MII 433GP back



Cyrix's failure is described by Glenn Henry CEO of Centaur Technology as "Cyrix had a good product, but they got bought by a 'big smokestack' company and they got bloated. When Via bought Cyrix, they had 400, and we had 60, and we were turning out more product."[5]


In June 2006, AMD unveiled the world's lowest-power x86-compatible processor that consumes only 0.9 W of power. This processor is based on the Geode core, demonstrating that Cyrix's architectural ingenuity still survives.




In popular media

The film Eraser featured a defense corporation known as "Cyrex". Cyrix became concerned about the potential name conflict, and contacted the film production company. The name was then retroactively digitally edited to become "Cyrez" to avoid any confusion.

In the Machinima "Freeman's Mind," Ross Scott as Gordon Freeman curses Cyrix processors as a computer breaks in Episode 3.[6]


  1. ^ "Manufacturer articles (Cyrix)". www.Coprocessor.info. Archived from the original on 2011-06-14. Retrieved .
  2. ^ "Cyrix Joshua Processor - From Peppers to the Bible | The CPU Shack Museum". www.cpushack.com. Retrieved .
  3. ^ "Microprocessor Forum: Cyrix spices up PC with Jalapeno - EDN".
  4. ^ "Cyrix Unveils Jalapeno Core Architecture". www.cpushack.com. Retrieved .
  5. ^ https://archive.linuxgizmos.com/glenn-henry-on-the-isaiah-architecture/
  6. ^ http://www.popflock.com/video?id=9jKc5wz3Jgw

External links




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