Centaur Technologies Inc. was founded in April 1995 by Glenn Henry, Terry Parks, Darius Gaskins, and Al Sato. The funding came from Integrated Device Technology, Inc. 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 from Intel's cores. Second, a unique management approach designed to achieve high productivity. While funded 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 the marketing name of VIA C3, as well as quite a number of designs for the VIA C7 processor and their latest 64-bit CPU, the VIA Nano. The VIA Nano design has been further refined and improved in chips produced by Zhaoxin. In late 2019 Centaur announced the "World’s First High-Performance x86 SoC with Integrated AI Coprocessor", the CNS core.
Design methodology
Centaur's chips historically have been much smaller than comparable x86 designs at their time, and they are thus cheaper to manufacture and consume less power. This made them attractive in the embedded marketplace. Centaur's design philosophy was always centered on "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. Centaur/VIA was among the first to design processors with hardware encryption acceleration in the form of VIA PadLock, starting with an 2004 VIA C7 release. Intel and AMD followed up with AES-NI in 2008, Intel SHA extensions in 2013, and RDRAND in 2015.
VIA C3
Because memory performance is the limiting factor in many benchmarks, VIA processors implement large primary caches, large TLBs, and aggressive prefetching, among other enhancements. While these features are not unique to VIA, memory access optimization is one area where features were not sacrificed to save die space. In fact, generous primary caches 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 clock cycles than on other x86 processors.
Rarely used x86 instructions are implemented in microcode and emulated as combinations of other x86 instructions. This saves die space and contributes to low power consumption. The impact upon the majority of real world application scenarios is minimal.
These design principles are derivative from the original RISC advocates, who claim that a smaller set of instructions, better optimized, can deliver faster overall CPU performance. The C3 design cannot be considered a pure RISC design because it accepts the x86 instruction set which is a CISC design.
VIA C7 Esther as an evolutionary step after VIA C3 Nehemiah+, 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 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 Nano
VIA Nano Isaiah is a combination of a number of firsts from Centaur, including their first superscalar out-of-order CPU and their first 64-bit CPU.
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.
CNS core
Centaur announced a new x86-64 "CNS" CPU with AVX-512 support and integrated AI coprocessor in late 2019.
NOTE: Even the 180 nm Duron Morgan core 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 smaller and cheaper to produce. As can be seen in this table, almost four C7 cores could be manufactured in the same area as a one P4 Prescott core on 90 nm process.
