9/30/2005 - High demand for PCI-Express-based COMs for all kinds of applications, large and small, has led Kontron to initiate a second round of COM Express standardization with the introduction of Compact COM Express. The goal is to build PCI-Express-based COMs on the smallest possible form factor and being achieved by the new Compact COM Express, based on the PICMG COM Express standard. A pure PCI version will first be available. The inclusion of PCI in the standard is particularly important to the developers of current systems because ETX, which was defined in 2000, offers PCI but does not support the latest processors & Bus speeds and there is a demand for a combination of these particular features. ADlink and Evalue already committed to the new Compact COM Express form factor. Kontron will launch the new 95x95cm standard Compact COM (Express) under the brands microETXexpress (for PCI-Express) and microETX (for PCI only).
The physical design of the new 95x95mm form factor differs from the COM Express standard only in its size and the addition of one extra mounting hole in the top right corner, for mounting the smaller board. ETXexpress (Basic COM Express) measures 118.75 cm² (100%), and microETXexpress (Compact COM Express) measures 90.25 cm² (76%). The even larger Extended ETXexpress (Extended COM Express) standard, whose specification was adopted along with ETXexpress, measures 170.5 cm² (143.58%). Of course, any feature that could not fit within the physical limits of the new, smaller COMs has been eliminated. What remains is the position of the X1 and X3 ETX connectors in relation to the baseboard. It was therefore possible to 'copy and paste’ many specification details, which is an advantage beyond just ease of documentation.
As far as the interface layout is concerned, in the new, compact 95x95mm microETX(express), the pinout for PCI and PCI Express will be on different interfaces. However, the other interfaces for peripherals, network, and storage – such as PCI, IDE, 10/100LAN, and 6x USB 2.0 – are mapped identically, so that, when changing from PCI to PCI Express or to a combination, as little as possible needs to be changed in the baseboard layout. Thus, users with an eye on future expansion can design PCI Express and SATA into their baseboards and make use of these features just when needed, simply by exchanging modules. Support for PCI and/or PCI Express is provided by the chipset. MicroETXexpress with SATA and PCI Express is already planned for 2006.
All three embedded formats (microETX, microETXexpress and ETXexpress (COM Express)) can be supported by a single baseboard, so the system is completely scalable in terms of processors, and from IDE to SATA, PCI to PCI Express, and 10/100 to GigaBitLAN. The layout of baseboards with PCI Express is simpler because there are fewer conducting paths per bus segment; this is a real advantage for developers.
With the launch of the new form factors for PCI and PCI Express-based designs Kontron is drawing a clear line to ETX designs and their derivatives. ETX supports up to Intel Pentium M 1.4 GHz and processors with similar energy consumption. Processors with higher performance that need to draw more power should be implemented via microETX(express) COMs; the performance limits of ETX will be reached significantly sooner than those of COM Express.
Kontron’s move to expand the COM Express specification to include smaller form factors is driven by the desire of users to pay today only for what they really need. For example, PC-based PLCs do not really need high-performance graphics cards with PCI Express x16 lanes but they do need high performance. For this reason, the two new standards are the ideal extensions to the product families developed around ETXexpress.
The specification, documentation, and manuals will be available for viewing under a Non-Disclosure Agreement from Q4 2005. The official design guide will be published as an open standard in January 2006. Experience tells that the PICMG standardization process could last until the end of 2006 or beyond, because procedures must be followed and discussions take time. However, because the new standard concepts are variants of COM Express, whose specifications were negotiated by the participating companies, it is unlikely that any major disagreements will arise; after all, all the participants are looking for the best, most-EMC compliant design. Moreover, PICMG has agreed in principle to support this type of expansion of the COM Express standard.
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