Centaur Technology
Encyclopedia
Centaur Technology is an x86
CPU design company, now a wholly owned subsidiary of VIA Technologies
, a member of the Formosa Plastics Group
, Taiwan
's largest industrial conglomerate.
, Terry Parks, Darius Gaskins, and Al Sato. The funding came from Integrated Device Technology
, Inc (IDT). The business goal was to develop compatible x86 processors that were much less expensive than Intel processors and consumed much less power.
There were two fundamental elements of the plan. First, a unique design, developed from scratch, of an x86 processor core optimized differently than Intel's cores. Second, a unique management approach designed to achieve high productivity.
While founded by IDT, three different Centaur designs were shipped under the marketing name of WinChip
. In September 1999, Centaur was purchased from IDT by VIA Technologies
, a Taiwanese company. Since then, five designs have shipped with marketing name of VIA C3
, quite a number of designs as the VIA C7
processor, and their latest 64-bit CPU, the VIA Nano
.
A significant performance gap exists between Centaur and competing x86 chips. Centaur design philosophy was always centered around "sufficient" performance for tasks that its target market demands. Some of the design trade offs made by the design team run contrary to accepted wisdom.
In a trend-setting move, processors were designed with hardware encryption acceleration starting with the VIA C7. Following its release many Intel and AMD processors incorporate this feature.
NOTE: Even the 180 nm Duron
Morgan core (106 mm²) with a mere 64 K secondary cache, when shrunk down to a 130 nm process, would have still had a die size of 76 mm². The VIA x86 core is clearly the smallest and cheapest to produce. As can be seen in this table, almost four C7 cores could be manufactured for the same cost as a single core P4 Prescott on 90 nm process; this because it costs about the same amount to manufacture a given surface area for most types of chip - with just over a quarter of the surface area of a Prescott P4, the VIA C7 costs around a quarter as much to manufacture.
X86 architecture
The term x86 refers to a family of instruction set architectures based on the Intel 8086 CPU. The 8086 was launched in 1978 as a fully 16-bit extension of Intel's 8-bit based 8080 microprocessor and also introduced segmentation to overcome the 16-bit addressing barrier of such designs...
CPU design company, now a wholly owned subsidiary of VIA Technologies
VIA Technologies
VIA Technologies is a Taiwanese manufacturer of integrated circuits, mainly motherboard chipsets, CPUs, and memory, and is part of the Formosa Plastics Group. It is the world's largest independent manufacturer of motherboard chipsets...
, a member of the Formosa Plastics Group
Formosa Plastics Group
Formosa Plastics Group is a Taiwanese conglomerate of diverse interests, including biotechnology, petrochemical processing and production of electronics components...
, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
's largest industrial conglomerate.
History
Centaur Technologies Inc. was founded in April 1995 by Glenn HenryGlenn Henry
Glenn Henry, named G. Glenn Henry, is a computer industry executive, cofounder of Centaur Technology, and holder of multiple computer patents. He was born in Berkeley, California, July 26, 1942.-Education:...
, Terry Parks, Darius Gaskins, and Al Sato. The funding came from Integrated Device Technology
Integrated Device Technology
Integrated Device Technology, Inc. is a publicly traded corporation headquartered in San Jose, California, that designs, manufactures, and markets low-power, high-performance mixed-signal semiconductor solutions for the advanced communications, computing, and consumer industries. The company...
, Inc (IDT). The business goal was to develop compatible x86 processors that were much less expensive than Intel processors and consumed much less power.
There were two fundamental elements of the plan. First, a unique design, developed from scratch, of an x86 processor core optimized differently than Intel's cores. Second, a unique management approach designed to achieve high productivity.
While founded by IDT, three different Centaur designs were shipped under the marketing name of WinChip
WinChip
The WinChip series was a low-power Socket 7-based x86 processor designed by Centaur Technology and marketed by its parent company IDT.-Design:The design of the WinChip was quite different from other processors of the time...
. In September 1999, Centaur was purchased from IDT by VIA Technologies
VIA Technologies
VIA Technologies is a Taiwanese manufacturer of integrated circuits, mainly motherboard chipsets, CPUs, and memory, and is part of the Formosa Plastics Group. It is the world's largest independent manufacturer of motherboard chipsets...
, a Taiwanese company. Since then, five designs have shipped with marketing name of VIA C3
VIA C3
The VIA C3 is a family of x86 central processing units for personal computers designed by Centaur Technology and sold by VIA Technologies. The different CPU cores are built following the design methodology of Centaur Technology.-Samuel 2 and Ezra cores:...
, quite a number of designs as the VIA C7
VIA C7
The VIA C7 is an x86 central processing unit designed by Centaur Technology and sold by VIA Technologies.- Product history :The C7 delivers a number of improvements to the older VIA C3 cores but is nearly identical to the latest VIA C3 Nehemiah core. The C7 was officially launched in May 2005,...
processor, and their latest 64-bit CPU, the VIA Nano
VIA Nano
The VIA Nano is a 64-bit CPU for personal computers. The VIA Nano was released by VIA Technologies in 2008 after five years of development by its CPU division, Centaur Technology...
.
Design methodology
While slower than x86 CPUs being sold by AMD and Intel, both in absolute terms and on a clock for clock basis, Centaur's chips are much smaller, cheaper to manufacture and consume less power. This makes them highly attractive in the embedded marketplace, and increasingly in the mobile sector as well.A significant performance gap exists between Centaur and competing x86 chips. Centaur design philosophy was always centered around "sufficient" performance for tasks that its target market demands. Some of the design trade offs made by the design team run contrary to accepted wisdom.
In a trend-setting move, processors were designed with hardware encryption acceleration starting with the VIA C7. Following its release many Intel and AMD processors incorporate this feature.
VIA Nano
- VIA Nano Isaiah (CN) is a combination of a number of firsts from Centaur, their first superscalar out-of-order CPU, their first 64-bit CPU from Centaur and their first processor designed from scratch.
- The development of the VIA Nano focused on radically improving the performance side of the performance-per-watt equation while still maintaining a similar TDP to the VIA C7.
VIA C7
- VIA C7 Esther (C5J) as an evolutionary step after VIA C3 Nehemiah+ (C5P), in which Centaur followed their traditional approach of balancing performance against a constrained transistor / power budget.
- The cornerstone of the VIA C3 series chips' design philosophy has been that even a relatively simple in-order scalar core can offer reasonable performance against a complex superscalar out-of-order core if supported by an efficient "front-end", i.e. prefetch, cache and branch prediction mechanisms.
- In the case of VIA C7, the design team have focused on further streamlining the "front-end" of the chip, i.e. cache size, associativity and throughput as well as the prefetch system. At the same time no significant changes to the execution core ("back-end") of the chip seem to have been made.
- The VIA C7 successfully further closes the gap in performance with AMD / Intel chips, since clock speed is not thermally constrained.
VIA C3
- Because memory performance is the limiting factor in many benchmarks, VIA processors implement large primary cacheCPU cacheA CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations...
s, large TLBsTranslation Lookaside BufferA translation lookaside buffer is a CPU cache that memory management hardware uses to improve virtual address translation speed. All current desktop and server processors use a TLB to map virtual and physical address spaces, and it is ubiquitous in any hardware which utilizes virtual memory.The...
, and aggressive prefetchingPrefetchingPrefetching may refer to:* Instruction prefetch, in computer architecture, a microprocessor speedup technique* Prefetch input queue , in computer architecture, pre-loading machine code from memory...
, among other enhancements. While these features are not unique to VIA, memory access optimization is one area where they have not dropped features to save die space. In fact, generous primary caches (128K) have always been a distinctive hallmark of Centaur designs.
- Generally, clock frequency is favored over increasing instructions per cycle. Complex features such as out-of-order instruction execution are deliberately not implemented, because they impact the ability to increase the clock rate, require a lot of extra die space and power, and have little impact on performance in several common application scenarios.
- The pipeline is arranged to provide one-clock execution of the heavily used register–memory and memory–register forms of x86 instructions. Several frequently used instructions require fewer pipeline clocks than on other x86 processors.
- Infrequently used x86 instructions are implemented in microcodeMicrocodeMicrocode is a layer of hardware-level instructions and/or data structures involved in the implementation of higher level machine code instructions in many computers and other processors; it resides in special high-speed memory and translates machine instructions into sequences of detailed...
and emulated. This saves die space and reduces power consumption. The impact upon the majority of real world application scenarios is minimized.
- These design principles are derivative from the original RISC advocates, who stated a smaller set of instructions, better optimized, would deliver faster overall CPU performance. The C3 design cannot be considered a RISC design because it uses the x86's CISCComplex instruction set computerA complex instruction set computer , is a computer where single instructions can execute several low-level operations and/or are capable of multi-step operations or addressing modes within single instructions...
instruction set for compatibility.
Comparative die size
| Processor | Secondary Cache (k) |
Die size 130 nm (mm²) |
Die size 90 nm (mm²) |
Die size 65 nm (mm²) |
|---|---|---|---|---|
| VIA Nano 1000/2000 | 1024 | N/A | N/A | 63.3 |
| VIA C3 / VIA C7 | 64/128 | 52 | 30 | N/A |
| Athlon XP | 256 | 84 | N/A | N/A |
| Athlon 64 | 512 | 144 | 84 | 77 |
| Pentium M | 2048 | N/A | 84 | N/A |
| P4 Northwood | 512 | 146 | N/A | N/A |
| P4 Prescott | 1024 | N/A | 110 | N/A |
NOTE: Even the 180 nm Duron
Duron
The AMD Duron was an x86-compatible microprocessor manufactured by AMD. It was released on June 19, 2000 as a low-cost alternative to AMD's own Athlon processor and the Pentium III and Celeron processor lines from rival Intel...
Morgan core (106 mm²) with a mere 64 K secondary cache, when shrunk down to a 130 nm process, would have still had a die size of 76 mm². The VIA x86 core is clearly the smallest and cheapest to produce. As can be seen in this table, almost four C7 cores could be manufactured for the same cost as a single core P4 Prescott on 90 nm process; this because it costs about the same amount to manufacture a given surface area for most types of chip - with just over a quarter of the surface area of a Prescott P4, the VIA C7 costs around a quarter as much to manufacture.