Cyrix Corporation was a microprocessor developer that was founded in 1988 in Richardson, Texas, as a specialist supplier of floating point units for 286 and 386 microprocessors. The company was founded by Tom Brightman and Jerry Rogers.
In 1992, Cyrix introduced its own i386 compatible processors, the 486SLC and 486DLC. These has higher performance than the Intel parts, but a lower price. They were primarily marketed to users looking to upgrade existing machines. Their release sparked a lengthy series of lawsuits with Intel while their foundry partner IBM was releasing the same designs under their own branding.
The combination of these events led Cyrix to begin losing money, and the company merged with National Semiconductor on 11 November 1997. National released Cyrix's latest designs under the MediaGX name and then an updated version as Geode in 1999. National sold the line to AMD in August 2003 where it was known as Geode. The line was discontinued in 2019.
History
At the end of March in 1992, the Cyrix Cx486SLC was released. It was a x86 microprocessor that was pin compatible with the 386SX and made for notebook computer applications. Following up shortly after in June of 1992, the Cx486DLC was released, a desktop version of the SLC that was pin-compatible with the 386DX.
Products
Cyrix FasMath coprocessors
The first Cyrix product for the personal computer market was a x87 compatible FPU coprocessor. The Cyrix FasMath 83D87 and 83S87 were introduced in November of 1989. The 83D87 was pin compatible with the Intel 80387, while the 83S87 was pin compatible with the 80387SX. Both provided up to 50% more performance, and additionally they had lower power consumption when idle, due to a low power operation. Upon release the 83S87 cost $506 for a 16-MHz version and $556 for a 20-MHz version. The Cyrix FasMath 82S87, a 80287-compatible chip, was developed from the Cyrix 83D87 and has been available since 1991.
486
Its early CPU products included the 486SLC and 486DLC, released in 1992, which, despite their names, were pin-compatible with the 386SX and DX, respectively. While they added an on-chip L1 cache and the 486 instruction set, performance-wise, they were somewhere between the 386 and the 486. The chips were mostly used as upgrades by end users looking to improve performance of an aging 386 and especially by dealers, who by changing the CPU could turn slow-selling 386 boards into budget 486 boards. The chips were widely criticized in product reviews for not offering the performance suggested by their names, and for the confusion caused by their naming similarity with Intel's SL line and IBM's SLC line of CPUs, neither of which was related to Cyrix's SLC. The chips did see use in very low-cost PC clones and in laptops.
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 Pentium Overdrive, the Cyrix 5x86 used 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.