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Oops...I Did the AMC Form Factor Again AdvancedTCA


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November 02, 2006

Oops...I Did the AMC Form Factor Again

TMCnet News,


The PCI Industrial Computer Manufacturers Group (News - Alert), or PICMG, has definitely scored a rash of success in recent years, advancing the CompactPCI hardware specifications with newer, more powerful form factors like AdvancedTCA (News - Alert), AdvancedMC and (most recently) MicroTCA.

Behind the organization that is PICMG are some of the most talented minds in the industry. But despite their combined superior intellect, those members are still inevitably humans who are, by their very nature, prone to making mistakes. Case in point: the Advanced Mezzanine Card spec.
AdvancedMCs, or just AMCs for short, were introduced in 2004 as a hotswappable add-on that fit into the AdvancedTCA (ATCA) carrier-grade single board computer. Their benefits became so significant that PICMG reverse-engineered their specs to make use of the AMC sans the ATCA board, resulting in the creation of the MicroTCA (News - Alert) spec. In fact, Intel announced last month it has used the AMC form factor as the foundation for its Intel NetStructure WiMAX Baseband Card.
But field engineers as early as last year began to discover a major problem with the AMC, industry officials told TMCnet. While the half-sized AMC form factor caused no noticeable glitches, the full-sized AMC actually conflicted with the ATCA boards they were designed to fit into.
“Handles were breaking off when AMCs were put into the ATCA boards,” explained Thanh Nguyen, Manager of Product Management at Emerson Network Power’s Embedded Computing business, formerly known as Artesyn Communication Products.
If you think the handle that secures the ATCA into the board chassis isn’t significant, think again! Those handles tie into a hot-swap switch on the circuit board. “When you put all four AMCs on it, there's really not much room left on the top,” Nguyen said.
As a result, PICMG members have been hastily working on a new Engineering Change Number, ECN-002. The redesign does offer other enhancements (wireless, throughput, etc.) but it primarily adds a new mid-sized form factor to the spec.
Examples of the new mid-sized form factor
Examples of the full-sized, mid-sized and half-sized AMC
“The problem became widely known in a lot of labs. The committee quickly got together to talk about that and find out how to solve that,” said Nguyen, who is not a member of PICMG’s AMC Working Group.
AMC ECN-002 is expected to be fully ratified by PICMG later this month. And, according to field engineers, the new design couldn’t come sooner as customers have been demanding the hardware fix for some time now. In fact, Emerson has already announced it will make available the new mid-size KosaiPM module, a Pentium-based AdvancedMC (News - Alert) card optimized for optical and wireless infrastructure systems, voice gateways, and SS7/SIGTRAN signaling systems that require high-speed control, protocol and packet processing.
Because the new mid-sized form factor is smaller than a full-sized card, it provides additional room for front panel LEDs and I/O on the ATCA carrier, which makes it easier for field service personnel to monitor and service rack-mounted ATCA blades, Nguyen added.
“We will support T1/E1 backhaul functionality,” he said.
More examples of mid-sized AMCs
A mechanical drawing example of the new mid-sized AMC
PICMG and its spokesman Rob Davidson have declined repeated requests to be interviewed for this article.
But another field engineer who was active in the development of MicroTCA declined to characterize the AMC’s flaws as a design defect. “It does get a little snug but defect is too strong a word. There really isn't enough tolerance put in,” explained Austin Hipes, field engineering manager at Alliance Systems (News - Alert).
Alliance Systems, which markets the NetStructure Card with Intel, has no intentions currently to switch into the mid-sized form factor. The WiMAX Baseband card, which will be available next month, is a full-sized, double-wide AMC that includes Open Base Station Architecture Initiative (OBSAI) interfaces and a full Media Access Controller (MAC) and Physical Layer (PHY) solution.
“Guys who just make AMCs for a living, you're going to see them stick with the full size. I don't think the mass AMC market is going to switch from full to mid,” Hipes said.
There are certain market segments where the new mid-sized AMC logically fit like fabric switch manufacturers that need a minimal amount of functionality on every switch but want to vary the processing power.
“Where I think mid-sized is important is for the guys who design ATCA boards that need them to be upgradeable,” he said.
Robert Liu is Executive Editor at TMCnet. Previously, he was Executive Editor at Jupitermedia and has also written for CNN, A&E, Dow Jones and Bloomberg. For more articles, please visit Robert Liu's columnist page.

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