Cyrix III is an

x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel based on the Intel 8086 microprocessor and its 8088 variant. The 8086 was introd ...

-compatible

Socket 370 Socket 370 (also known as the PGA370 socket) is a CPU socket first used by Intel for Pentium III and Celeron processors to first complement and later replace the older Slot 1 CPU interface on personal computers. The "370" refers to the number of ...

CPU.

VIA Technologies VIA Technologies Inc. (), is a Taiwanese manufacturer of integrated circuits, mainly motherboard chipsets, CPUs, and memory. It was the world's largest independent manufacturer of motherboard chipsets. As a fabless semiconductor company, VIA c ...

launched the processor in February 2000. VIA had purchased both Centaur Technology and

Cyrix 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 19 ...

. Cyrix III was to be based upon a core from one of the two companies.

History

The Cyrix III was launched in late February 2000. It was initially based on the Joshua core, and was available in two performance ratings of 500 and 533 MHz, with the PR500 being $84 per unit and the PR533 $99. National Semiconductor would be the producer of the chips. 650 and 677 MHz versions of the Cyrix III were available starting January of 2001. The 650 MHz version would cost $55 per chip while the 677 would be $60 and both were based on the Samuel core. The 700 MHz version of the Cyrix III was available on January 19, 2001. The price would be $62 per chip in bulk quantities. This was the last III chip released using the Samuel core, as the Samuel II was expected to be released in March. Just a month later in February 2001, Cyrix III chips based on the Samuel 2 core were announced. An initial 750 MHz version would be available, with 800 and 850 MHz coming later. The chips would have a 100 and 133 MHz FSB, 128 KB of L1 cache along with MMX and 3DNow instructions. The chips would be produced using a 0.15 micron process and have a die size of 52 square mm. VIA planned to release a later version of the chip, code-named Ezra/C5C with a 0.13 micron process and speeds of 750 MHz up to possibly 1 GHz.

CPU cores

Joshua

The pre-release Cyrix III CPUs were based upon a 22 million transistor Joshua core designed by

. This CPU core was a typical Cyrix design:

superscalar A superscalar processor is a CPU that implements a form of parallelism called instruction-level parallelism within a single processor. In contrast to a scalar processor, which can execute at most one single instruction per clock cycle, a sup ...

with

speculative execution Speculative execution is an optimization technique where a computer system performs some task that may not be needed. Work is done before it is known whether it is actually needed, so as to prevent a delay that would have to be incurred by doing t ...

and a high IPC rate but rather low clock rates. To emphasize the higher performance of their designs compared to the competitors' offerings, Cyrix used a system with a " P-Rating" higher than the clock rate. The

floating point In computing, floating-point arithmetic (FP) is arithmetic that represents real numbers approximately, using an integer with a fixed precision, called the significand, scaled by an integer exponent of a fixed base. For example, 12.345 can be ...

unit of the processor had supposedly been updated from the lacklustre unit in the 6x86/MII series.Lok
Joshua
Ars Technica, accessed May 11, 2007. When the chip reached reviewers, the weighted integer/floating-point performance was found to be fairly low compared to the competition. The fact that Cyrix 6x86-line were only 486-compatible, not 100% Pentium-compatible, intensified the negative attention at this point.

Samuel

Because the Joshua core was such a mixed result in thermal output, core size, and performance, VIA switched almost immediately to an 11 million transistor Samuel core designed by Centaur Technology.Witheiler, Matthew

The New VIA Cyrix III: The Worlds First 0.15 Micron x86 CPU], Anandtech, January 5, 2001. The Samuel core was a simpler design, being an evolution of the

WinChip The WinChip series was a low-power Socket 7-based x86 processor designed by Centaur Technology and marketed by its parent company IDT. Overview Design The design of the WinChip was quite different from other processors of the time. Instead o ...

processors (the unreleased WinChip 4). Samuel was designed for higher clock speeds, with more L1 cache (but no L2), and used smaller manufacturing technology.De Gelas, Johan
Cyrix III, An Alternative Approach
, Ace's Hardware, August 6, 2000. While this version of Cyrix III still had sub-par performance compared to the competition from Intel and AMD, it was quite power efficient and consisted of only half the number of transistors of Cyrix's creation.Poluvyalov, Alexander
VIA Cyrix III (Samuel 2) 600 and 667 MHz
, Digit Life, accessed May 12, 2007. VIA dropped the criticized P-Rating with new processors based on the Samuel core, in favor of simply distinguishing them by their actual clock speed.

Samuel 2

The Samuel 2 core is a revision to the Samuel core. The Centaur Technology team added an on-die 64 KiB L2 cache and moved to a 150 nm manufacturing process. These changes improved per-clock performance, reduced power demands, and increased clock speed scalability.

Models & variants

Renaming

The Cyrix III was later renamed C3, as it was not built upon Cyrix technology at all.

References

External links

Cyrix III at CPU-World

VIA Cyrix III (Samuel 2) 600 and 667 MHz
{{VIA 3 Cyrix 3