By Charles J. Murray
The VMEbus seems set to emerge revitalized from the deep freeze of the downturn as developers ready technologies that give the workhorse bus of military, aerospace, and telecom applications a bandwidth boost.
At the Bus & Board/2004 Conference, VME vendors are laying the groundwork for the addition of high-speed switch fabrics by rolling out new VME boards and connectors based on an up-and-coming technology called the VMEbus Switched Serial Standard (VXS).
A cadre of board makers---including Dy4 Systems (Kanata, Ontario, Canada), Mercury Computer Systems (Chelmsford, Mass.), Radstone Technology (Woodcliff Lake, New Jersey), and Vista Controls (Santa Clarita, Calif.)---will also team up in support of a separate fabric-based VME standard.
Tundra Semiconductor (Ottawa, Canada) will set the stage for another VME performance boost by unveiling a bridge chip developed by Motorola Computer Group (Tempe, Ariz).
A Common Goal
While the new VME technologies compete with one another on some levels, all systems share a common goal: greater bandwidth. "Twenty years ago, VME's 40 Mbytes/second was considered a high throughput rate," notes Jerry Gipper, director of marketing for Motorola Computer Group.
"But people continue to demand higher and higher data rates between system nodes, and the beauty is that a 20-year-old technology can provide it."
Indeed, VME's new alphabet soup of connections is expected to help it maintain its traditional customer base in defense and aerospace, while reviving the telecom business that dried up during the past two years. Some in the VME community even foresee VXS' use in such ultrahigh-performance applications as supercomputing.
"With VXS we can build a very high-speed, teraflops supercomputer in a 19-inch rack," says Ray Alderman, executive director of the VME International Trade Organization (VITA). "VXS allows you to hook a lot of processors together."
Alderman predicts that VME technology overall will grow 3% to 5% this year, mainly by riding the coattails of its primary customer---the military's commercial off-the-shelf market. Alderman predicts 15% to 20% growth for military COTS in 2004.
"From VME's standpoint, the bloodbath is over," Alderman says. "The decline in VME shipments, even in telecom applications, has bottomed out."
Industry analysts are less optimistic about VME's immediate future, saying the market is unlikely to grow in 2004 and may even decline. But they acknowledge that VME didn't take as bad a whupping as its more telecom-centric cousins, PCI and CompactPCI, during the slump.
Research firm Venture Development Corp. (Natick, Mass.) says that VME dipped about 10% from its 2001 revenues of $890 million, while CompactPCI fell 23% from 2001's $700 million total to $540 million at the end of 2002.
The main reason for VME's stronger showing is that nearly half of its customers are in defense and aerospace, Venture Development analysts said.
Many VME suppliers aren't content, however, to maintain the status quo by focusing on defense and aerospace. They're hoping that a redundant point-to-point switch fabric architecture will boost VME's performance enough to help it compete with AdvancedTCA (Advanced Telecom Computing Architecture), which has garnered the support of much of the telecom industry.
VME supporters point out that there's a precedent for their optimism, because 30% of VME's revenues came from telecom as recently as two years ago.
The emerging VXS, based on the recently ratified VITA 41 standard, offers a way to increase bandwidth on a VMEbus while allowing the VME parallel bus and the switch serial fabric to coexist. VXS does that by adding a so-called P0 connector in the inch-and-a-half gap between the existing P1 and P2 connectors on conventional VME64X backplanes. By putting the new high-density, high-signal-integrity connector onto existing VME boards, engineers set the stage for the fabric interconnect.
"If you're a VME user, the neat thing about VXS is that it adds to the VMEbus in a way that allows you to preserve your investment in the technology," Gipper says.
Motorola has tabbed VXS as a cornerstone of its VME Renaissance, a program launched in 2002 that aims to boost VME performance. In its literature, Motorola has said that VXS will provide "bandwidth, bandwidth, bandwidth," reaching individual transaction levels 50 times greater than that of VME64 parallel buses.
The company has also said that aggregate bandwidth in a VXS chassis could exceed VME64 by 900 times.
At Bus & Board, Bustronic Corp. (Fremont, Calif.) will unveil its VXS Switched Serial Backplane. Compatible with the VITA 41.0 spec and backward-compatible with VME64X, the backplane offers the P0 connector and can run such high-speed signals as RapidIO, PCI Express, and StarFabric.
Similarly, Positronic Industries (Springfield, Mo.) will show its VPX power connector, designed for VITA 41 VXS.
"VXS will be a factor in slowing the decline of VME," says Eric Gulliksen, project director at Venture Development. "But we won't know how much of a factor it will be until it gets out in the market and we see how it's received."
A separate group of suppliers will also lend their support this week to a VME-based technology that takes a slightly different approach to switch fabrics. Dy4 Systems, Mercury Computer Systems, Radstone Technology, and Vista Controls will jointly announce support for the proposed VITA 46 standard, which calls for switch fabric technology but concurrently enables high-speed backplane I/O and provides fast signals for legacy VME and PCI protocols. The announcement is expected to emphasize the use of VME in military systems.
Members of the group say the emphasis on I/O distinguishes their technology from VXS, but they add that there will be a market for both technologies.
"There are people who don't need high-speed I/O and who value backward compatibility a lot more," notes Rich Jaenicke, director of product management for Mercury Computer Systems. "But we think there are a lot of applications that need high-speed I/O in addition to switch fabrics."
Play It Cool
The drive toward VME performance is also being aided by cooling techniques that let users pack more processing power in a smaller area. VME boards that employ liquid cooling dissipate more than 100 watts/square inch, compared with about 1.5 W/inch2 for air-cooled architectures.
VITA's Alderman said Cray Research (Eagan, Minn.) used liquid cooling to dissipate 850-W on a 3 x 3-inch die in a supercomputing application. ISR (Clarkston, Wash.) is demonstrating its spray cooling technology at Bus & Board.
For its part, Tundra Semiconductor will add to the VME performance emphasis at Bus & Board when it rolls out its Tsi148 VME-to-PCI-X bus bridge chip, a product based on Motorola's Tempe application-specific IC. Tundra, which will market and manufacture the chip by agreement with Motorola, says the part will boost the performance bandwidth of the VME parallel bus to 320 Mbytes/s, an eightfold improvement over VME64's 40 Mbytes/s.
"This is the first major improvement on the chassis in a decade," says Tim Warland, product manager for Tundra Semiconductor. Warland said he expects the bridge chip to be used by board makers as well as by defense and aerospace contractors, such as Raytheon and Lockheed-Martin, which typically design around the VME topology.
Such defense and aerospace applications are expected to continue to be VME's bread and butter, even as the technology's performance rises.
"The VMEbus has been around since 1980, and the military has always used it," says Justin Moll, marketing manager of Bustronic. "And since it has always worked for them in the past, we expect them to continue using it."