Centaur Technology

• 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 (128KB) 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 on 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.
• In addition to x86, these processors support the undocumented Alternate Instruction Set.

• 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 focused on further streamlining the "front-end" of the chip, i.e. cache size, associativity and throughput as well as the prefetch system.[6] 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 Nano Isaiah (CN) 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.

Centaur announced a new x86-64 "CNS" CPU with AVX-512 support and integrated AI coprocessor in late 2019.[2] The CNS CPU was cancelled in 2021 when VIA sold its Centaur division to Intel.[7] The CNS core CPUs had up to 8 cores and ran at a 2GHz base frequency. It used the same LGA2011 pin socket as Intel's LGA2011-3 CPUs, however it is not electrically compatible with Intel motherboards. The CNS CPU cores were made on the TSMC 16nm node. Some of the advancements made on CNS were later used in some Zhaoxin Semiconductor CPUs in which VIA is in a joint venture with.[8]

Note: Even the 180 nm Duron Morgan core (106 mm²) with a 64K 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.