The VIA C7 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 intr ...

central processing unit A central processing unit (CPU), also called a central processor, main processor or just Processor (computing), processor, is the electronic circuitry that executes Instruction (computing), instructions comprising a computer program. The CPU per ...

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 ...

Product history

The C7 delivers a number of improvements to the older

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. In addition to ...

cores but is nearly identical to the latest VIA C3 Nehemiah core. The C7 was officially launched in May 2005, although according to market reports, full volume production was not in place at that date. In May 2006 Intel's

cross-licensing A cross-licensing agreement is a contract between two or more parties where each party grants rights to their intellectual property to the other parties. Patent law In patent law, a cross-licensing agreement is an agreement according to which two ...

agreement with VIA expired and was not renewed, which was the reason for the forced termination of C3 shipments on March 31, 2006, as VIA lost rights to the socket 370. The C7 appears still to be found in the marketplace, for example, on the bargain-priced

Everex Everex ("Ever for Excellence!") is a defunct American manufacturer of desktop and notebook personal computers. It was established in 1983 and headquartered in Fremont, California. The company was founded by Steve Hui, John Lee and Wayne Cheung ...

TC2502, sold by

Walmart Walmart Inc. (; formerly Wal-Mart Stores, Inc.) is an American multinational retail corporation that operates a chain of hypermarkets (also called supercenters), discount department stores, and grocery stores from the United States, headquarter ...

with a Linux distribution preinstalled and on the HP Mini-Note. A 1 GHz C7 processor with 128kB of cache memory is used in VIA's own PX10000G motherboard which is based on the proprietary

Pico-ITX In computer design, Pico-ITX is a PC motherboard form factor announced by VIA Technologies in January 2007 and demonstrated later the same year at CeBIT. The formfactor was transferred over to SFF-SIG in 2008. The Pico-ITX form factor specificatio ...

form factor. The chip is cooled by a large heatsink that covers most of the board and a small 40mm fan. In early April 2008 the schoolroom-use oriented, ultra-portable

HP 2133 Mini-Note PC The HP 2133 Mini-Note PC was a full-function netbook aimed at the business and education markets. It was available with SUSE Linux Enterprise Desktop, Windows Vista or Windows XP. Its retail price started at US$499 for the Linux version with 4 ...

family debuted with an entirely VIA-based, 1.0, 1.2 and 1.6 GHz C7-M processor portfolio, where the lowest speed model is optimized for running an SSD-based 4GB

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, w ...

distribution with a sub $500 price tag, while the middle tier carries

Windows XP Windows XP is a major release of Microsoft's Windows NT operating system. It was released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Windows 2000 for high-end and ...

and the top model comes with

Windows Vista Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...

Business, factory default. HP chose the single-core VIA C7-M CPU in order to meet the already fixed $499 starting price, even though Intel's competing Atom processor line debuted on 2 April 2008. The C7 is sold in five main versions: * C7: for desktops / laptops (1.5-2.0 GHz) - FCPGA Pentium-M package, 400, 533, 800 MHz FSB * C7-M: for mobiles / embedded (1.5-2.0 GHz) - NanoBGA2, 21mmx21mm, 400, 800 MHz FSB * C7-M Ultra Low Voltage: for mobiles / embedded (1.0-1.6 GHz) - NanoBGA2, 21mmx21mm, 400, 800 MHz FSB * C7-D: similar to original C7, but

RoHS The Restriction of Hazardous Substances Directive 2002/95/EC (RoHS 1), short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, was adopted in February 2003 by the European Unio ...

-compliant and marketed as "carbon-free processor". Some variants do not support

PowerSaver VIA LongHaul is a CPU speed throttling and power saving technology developed by VIA Technologies. By executing specialized instructions, software can exercise fine control on the bus-to-core frequency ratio and CPU core voltage. When the system ...

* Eden: Some

VIA Eden VIA Eden is a name of a variant of VIA's C3/ C7 x86 processors, designed to be used in embedded devices. They have smaller package sizes, lower power consumption, and somewhat lower computing performance than their C equivalents, due to reduced c ...

CPUs are based on a C7 core with low power consumption, package size, and clock rates as low as 400 MHz.

CPU cores

Esther

The Esther (C5J) is the next evolution step of the Nehemiah+ (C5P) core of the

line-up. New Features of this core include: * Average power consumption of less than 1 watt. * 2 GHz operation and a TDP of 20 watts. * L2 cache increased from 64k to 128k, with associativity increased from 16-way set associative in C3 to 32-way set associative in C7. * VIA has stated the C7 bus is physically based upon the Pentium-M 479-pin packaging, but uses the proprietary VIA V4 bus for electrical signalling, instead of Intel’s AGTL+ Quad Pumped Bus, avoiding legal infringement. * "Twin Turbo" technology, which consists of dual PLLs, one set at a high clock speed, and the other set at a lower speed. This allows the processor's clock frequency to be adjusted in a single processor cycle. Lower switching latency means that more aggressive regulation can be employed. * Support for SSE2 and

SSE3 SSE3, Streaming SIMD Extensions 3, also known by its Intel code name Prescott New Instructions (PNI), is the third iteration of the SSE instruction set for the IA-32 (x86) architecture. Intel introduced SSE3 in early 2004 with the Prescott revis ...

extended instructions. *

NX bit The NX bit (no-execute) is a technology used in CPUs to segregate areas of memory for use by either storage of processor instructions or for storage of data, a feature normally only found in Harvard architecture processors. However, the NX bit i ...

in PAE mode that prevents

buffer overflow In information security and programming, a buffer overflow, or buffer overrun, is an anomaly whereby a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory locations. Buffers are areas of memo ...

software bugs from being exploitable by viruses or attackers. * Hardware support for

SHA-1 In cryptography, SHA-1 (Secure Hash Algorithm 1) is a cryptographically broken but still widely used hash function which takes an input and produces a 160-bit (20- byte) hash value known as a message digest – typically rendered as 40 hexadec ...

and

SHA-256 SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compressi ...

hashing. * Hardware based " Montgomery multiplier" supporting key sizes up to 32K for

public-key cryptography Public-key cryptography, or asymmetric cryptography, is the field of cryptographic systems that use pairs of related keys. Each key pair consists of a public key and a corresponding private key. Key pairs are generated with cryptographic alg ...

Design choices

* C7 Esther as an evolutionary step after C3 Nehemiah, in which VIA / Centaur followed their traditional approach of balancing performance against a constrained transistor / power budget. * The cornerstone of the 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 In computer architecture, a branch predictor is a digital circuit that tries to guess which way a branch (e.g., an if–then–else structure) will go before this is known definitively. The purpose of the branch predictor is to improve the flow ...

mechanisms. * In the case of 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. * The C7 successfully further closes the gap in performance with AMD / Intel chips, since clock speed is not thermally constrained.

References

External links

*
Review of the EPIA EN15000 with VIA C7 Processor

VIA C7 Processor

VIA C7-M Processor

Detailed Platform Analysis in RightMark Memory Analyzer. Part 12: VIA C7/C7-M Processors, translated in English
* http://www.cpushack.com/VIA.html * https://www.pricenfees.com/digit-life-archives/via-cyrix-iii-samuel-2-600-667-mhz * https://web.archive.org/web/20060615180950/http://www.sandpile.org/impl/c5xl.htm {{DEFAULTSORT:Via C7 C7 Embedded microprocessors