The single-board computer wars

Aug. 1, 1997
VME continues to dominate despite the growing impact of CompactPCI, while PCI mezzanine cards gain ground in their battle with IndustryPack

VME continues to dominate despite the growing impact of CompactPCI, while PCI mezzanine cards gain ground in their battle with IndustryPack

By John McHale

Electronic systems designers who are still seeking out the VME backplane data bus and printed circuit boards are demanding more power, speed, and versatility. And the VMEbus continues evolving to meet those demands, in the face of competition from CompactPCI.

Demand for VME is turbocharging what historically has been a slow-moving industry. Development of the 160 megabyte-per-second 2e VME data bus and boards as well as the upcoming 320 megabyte-per-second VME320 are at the core of the most important changes in the VME business.

VME, a longtime open-systems standard, represents a market-driven environment, says Ray Alderman, executive director of the VME International Trade Association (VITA) in Scottsdale, Ariz. The customers want products that are increasingly fast, powerful, and easily configurable with plug-and-play features, as well as that have the capability to "hot swap" boards to and from operating backplanes.

Another recent development that adds versatility to VME is the PCI mezzanine card, better-known as PMC. This daughter card, although physically larger than its IndustryPack brethren, enables VME systems designers to take advantage of the popular PCI bus and existing software that is compatible with PCI.

Jerry Krasner, director of computer and telephony technology marketing at market researcher Venture Development Corp. in Natick, Mass., points out that many strong technologies can be overlooked if the market is not asking for them.

One of the major issues in single-board and mezzanine-board computers today is versatility, says Chris Parr, major markets manager at Matrix Corp. in Raleigh, N.C. "We produce a pretty standard board and for each customer all we have to do is tweak it a little bit to fit their application."

Engineers at Matrix are providing their customers with 6U VMEbus CPU360 multiprotocol processor engine, containing a Motorola MC68360 integrated microprocessor, for control and communications applications.

The MC68360 combines an enhanced Motorola CPU32+ core processor module, which runs 68000 instructions, with on-chip timers, flexible I/O channels with direct memory access support, and other system-level functions. It has six serial channels of configurable I/O and a 16-bit parallel port.

The use of the Motorola-Toshiba 3150 NEURON chip on the board, which enables the user to implement control networks with a Lonpalk network link between devices, provides for maximum system throughput rates. Its on-chip firmware implements a protocol for a flexible real-time network based on the OSI model. The CPU360 is available in industrial, extended-temperature, and rugged versions.

Another issue of keen interest to VME systems designers is long-term support and resistance to rapid obsolescence, says Harry White, president of VI Computer in Encinitas, Calif. "Having the same part available two years down the road, that`s what our customers are looking for."

White`s experts at VI have announced a new PowerPC 604e-based VME single-board computer called the Power 4e. The performance of the VI PowerPC 166 MHz and 200 MHz boards is estimated at 6.5 SPECint95 and 6.1 SPECfp95.

VI`s Power 4e features a PCI local mezzanine bus and PMC card connector, as well as the 80 megabyte-per-second VME64 interface, which White says brings integration, I/O performance, flexibility, and processing power to his VME systems customers.

COTS - the U.S. Defense Department commercial-off-the-shelf initiative launched three years ago-continues to be a major driver in the market, experts say.

Technological leaders at U.S. government agencies such as the DOD, Federal Aviation Administration, and National Aeronautics and Space Administration are moving closer to COTS, but are still going slowly in many applications, particularly when it comes to real-time software running on VME systems, Alderman says. "They do not trust it," Alderman points out. "There are too many safety features with avionics. You don`t want to be at 15,000 feet and have windows NT crash on you."

The government is diminishing its reliance on mil-spec equipment and substi tuting more COTS products, especially as supplies and the number of manufacturers of mil-standard parts diminish, says Duncan Young, director of marketing at DY 4 Systems in Kanata, Ontario. COTS products also are becoming more reliable and rugged, Young says.

Young`s engineers have developed a rugged PowerPC 604e-based VME single-board computer with connectors for two air- or conduction-cooled PMC modules for real-time military/aerospace applications in harsh conditions.

The new SVME/DMV-178 offers a choice of PowerPC 604e or 603eV RISC CPU running at standard speeds of 200 MHz, with higher speeds available.

Its dual-PMC interfaces provide features and functions in a single 6U VME slot normally requiring multiple boards.

The SVME/DMV-178 features Autostore NOVRAM, which upon power failure (or power down), transfers the entire contents of the memory to the on-chip SRAM and stores to the on-chip EEPROM. Data automatically transfers back to the SRAM for use by the application when power flow resumes.

Another computer company providing ruggedized boards for excessive temperature environments is Themis Computers in Fremont, Calif. Themis engineers have implemented a vapor-phase cooling in their ColdLogic system that enables designers to use high-density COTS VMEbus boards in harsh environments.

The system mists the interior of the enclosure with a dialectric fluid that vaporizes on contact with the heated electronics. It carries the heat away to the walls of the enclosure where it condenses and recycles back into the spray.


CompactPCI, which represents the marriage of three well-accepted and mature technologies - PCI Local Bus, Eurocard mechanics, and pin and socket connectors - is growing quickly despite the naysayers in the VME hierarchy.

It has a processor-independent bus and is more rugged and expandable than a desktop PC. In simpler terms, CompactPCI is the application of standard PCI Local Bus technology, PCI bus interface silicon and software, to the Eurocard mechanical form-factor popularized by VMEbus.

CompactPCI attains the ruggedness and reliability of the Eurocard form-factor - specifically, the combination of pin- and socket connectors, card guides, and front- panel retaining mechanisms. This mechanical arrangement is generally not prone to suffer the loss of electrical contact in high- vibration and shock environments. It also provides solid tactile feedback during insertion, therefore ensuring that a board is properly engaged in the system.

Other CompactPCI strengths include its throughput and its burst oriented nature.

Military systems designers however, will still look towards VME because of a large installed base of VME hardware and software in military systems, and because of the military`s traditional resistance to change.

VME`s strong point is its 16 years of quality products and availability.

CompactPCI is not applicable to mission-critical applications because it cannot perform multiprocessing, claims VITA`s Alderman.

The telephony industry is pushing the hardest toward CompactPCI because of its compatibility with the desktop, notes Venture Development`s Krasner.

officials of some companies see a strong financial future with CompactPCI and are switching from VME over to the newer product. One such company is Alacron in Nashua, N.H.

Joe Sgro, president of Alacron, says CompactPCI is the future in the industry. It offers a rugged product that gives a lot of play and has strong throughput, he says.

Alacron`s engineers offer the FT-2106x CompactPCI board which uses a scaleable array of as many as eight Analog Devices SHARC digital signal processors, interconnected using Alacron`s dual-ported local memory architecture. The dual-ported local memory design eliminates processor contention for off-chip memory, enabling the memory bandwidth of the SHARC array to scale linearly with the number of SHARC processors, Sgro says.

It uses a dedicated Intel Pentium P5 processor to perform operating system functions, thereby freeing the SHARC array for data processing.

Alderman, however, calls small companies like Alacron that are switching to CompactPCI, "organ donors." They will get eaten by the big companies like Motorola and Ziatech, Alderman says, because each company is going to have a different standard and there will be no compatibility between parts The small companies, therefore, will not be able to survive, Alderman predicts.

Venture Development`s Krasner, however, says he believes CompactPCI will play a strong part in many designs, and be around for years to come.

Engineers at one of the big companies that Alderman mentioned, Ziatech in San Luis Obispo, Calif., are offering what they claim is the first two-slot, single-board solution with dual Pentium pro processors on CompactPCI.

The board drives the two buses at 33 MHz and operates in symmetric multiprocessing mode. It has as much as 512 Megabytes of DRAM, 8 megabytes of flash memory, and 20 to 85 megabytes of flash disk expansion.

It also is a drop-in upgrade for Ziatech`s ZT 5510 CPU board with Pentium processor.

The PowerPC continues to be a strong factor in the single board industry, says Alderman, who predicts it will end up replacing the Motorola 68000 machines as the standard. But there will still be a strong legacy towards the 68000.

The PowerPC took a minor setback when Microsoft leader Bill Gates decided not support it with his Windows NT operating system, Krasner points out. "Whenever the major driver in the market, like Windows NT does not support your machine, it will hurt your business."

Motorola officials say the Microsoft decision not to support PowerPC was a business decision. "It was simply a matter of money, says Jerry Gipper, director of marketing for embedded technologies at Motorola. "Gates saw a seven-figure income as opposed to a six-figure income."

PowerPC engines continue to grow, taking up about 17 percent of the microprocessor market last year, Krasner says.


The mezzanine card industry remains stable with PCI Mezzanine Card (PMC) and IndustryPack (IP) splitting the market. Mezzanine cards mesh different types of I/O, control, and interface functions on the same board.

PMC is a small mezzanine card that attaches to a connector on a VME, Multibus, or CompactPCI board and sits parallel to the board. PMCs are conceptually and mechanically similar to SBus peripheral cards. Essentially, PMC is a high-performance, low-profile, peripheral expansion card for single-board computers.

IndustryPack , developed by engineers at GreenSpring Computers in Menlo Park, Calif., specifies the electrical, mechanical, and logical definitions for mezzanine modules. IP modules mount parallel to a host carrier board, which provides host processor or primary bus interfacing, as well as a mechanical means for connecting the IP module`s I/O to the outside world.

Kim Rubin, vice president at GreenSpring, says he cannot see why anyone would choose PMC except for its ability to work with inexpensive components.

"It`s dumb," he claims. "It takes up nearly half your board and only utilizes a third of the space. IndustryPack takes up less space with more efficiency."

Rubin`s engineers have developed a new high-speed fiber-optic communication system which transfers data from node to node at speeds as fast as 10.6 megabytes per second. The IP-FiberIO IndustryPack consists of a fiber-optic shared memory interface on a Type III double-wide IndustryPack mezzanine module.

Each IP node carries 512 Kbytes of RAM mapped into the address space.

The IP-FiberIO helped designers at simulation vendor FlightSafety International in New York replace wiring with fiber optics which are not subject to electrical noise and can run a long distance - 12 miles in this case - with a zero error rate.

While IndustryPack is continuing to see a majority of the business, PMC is here to stay, Krasner says - "if for nothing else than its compatibility with CompactPCI."

The PMCspan board from the Motorola Computer Group in Tempe, Ariz., enables users to customize their exact I/O requirements with Motorola`s VME-based CPU modules designed around the PowerPlus Architecture.

When coupled with Motorola processor module, the PMCspan provides as many as six PMCs - more expansion capability than any other VMEbus processor module, Motorola officials say. Each PMCspan supports either two single-wide or one double-wide PMC.

By stacking PMCspans, designers can add as many as four additional single-wide PMCs to Motorola`s compute engines - either immediately or as future application growth demands. The PMCspan is a standard 6U single-slot VMEbus module that links to its host board via a PCI expansion connector. It supports front panel and P2 I/O access for customer supplied PMCs.

Who`s doing what

Officials at Dynatem in Mission Viejo, Calif., are porting the QNX real-time operating system to their VMEbus-based PC card, the DPC1. It takes advantage of QNX`s networking and graphics capabilities.

designers ported the Photon microGUI to the DPC1`s SVGA controller; 100BaseT Ethernet and VMEbus backplane networking are supported. All standard PC I/O such as COM1/COM2, mouse and keyboard, IDE and floppy drive mass storage, as well as fast wide SCSI are implemented in the QNX system.

Among the features of QNX are scalability, compactness, and built-in distributed processing. This real-time operating system provides multi-node transparent networking that enables processor boards to gain access directly to resources on other processor cards through Ethernet, backplane, and PMC add-in physical interfaces.

Engineers at CETIA in Cambridge, Mass., are offering a new 200 MHz version of the company`s PowerEngine CVME 603e VME single-board computer. The CVME 603e features a PowerPC 603e CPU plus two PMC sites on a single-slot 6U VME board.

Standard features for the board include as much as 128 megabytes of DRAM; as much as 1 megabyte of flash boot memory; an integrated VME64-to-PCI bridge; two serial ports and a parallel printer port; an Ethernet interface; keyboard and mouse interfaces; a Fast SCSI interface; and 16-bit stereo audio I/O.

The series also is available with the Ruggedizer, CETIA`s laser-matched add-on thermal drain that extends the board`s overall operating range and mechanical strength.

Scientists at Themis have introduced the USP-1 VME64 Engine, an UltraSPARC-based VME Single Board Computer. Based on the Sun Microsystems Ultra(tm)1 Workstation design, the USP-1 has workstation features that are 100 percent Sun compatible. The USP-1 uses the Sun UltraSPARC-1 processor and support chip set to provide Ultra(tm)1 Workstation equivalent performance.

The USP-1 has two metal stiffeners to eliminate board flex and to ensure the integrity of the board in high-vibration environments.

Experts at CSPI in Billerica, Mass., are introducing the MAP-2640, a new high-performance, high-density VME 6U board for their MAP Network Multicomputing product line. The MAP-2640 combines Myrinet gigabit network technology with the PowerPC 603 architecture and the P0 VME64 extension connector.

CSPI designers support the MAP Series with an open Multiprocessing software package including: the VxWorks real-time operating system and development tools, MPI Parallel Programming Library, and CSPI`s Signal Processing Library.

The board packs into one 6U slot with four PowerPC processing nodes, four Myrinet network processors, one Myrinet eight-port switch, and four Myrinet SAN links. It delivers 1.6 GFLOPS of peak processing power and 1.28 gigabytes per second of I/O.

Engineers at Teknor Industrial Computers Inc. in Montreal have launched the PCI-936, an integrated Pentium industrial single-board computer that is compatible with standards of the PCI Industrial Computer Manufacturers Group in Wakefield, Mass - better known as PICMG.

The unit features a high-speed Intel microprocessor, integrated IDE and PCI Fast-20/SCSI II interface, 10/100Base-T Ethernet connectivity, flat panel/CRT video, and a list of I/Os including two Universal Serial Bus (USB) ports.

The PCI-936 uses thermal management circuitry to sense CPU temperature, and a two-stage watchdog timer that checks itself before sending a reset signal to the system.

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Scientists at Themis Computers in Fremont, Calif., have intoduced the USP-1 VME64 Engine, an UltraSPARC-based VME single board computer based on the Sun Microsystems Ultrafi1 workstation design.

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Engineers at Greenspring Computers in Menlo Park, Calif. developed the IP-Fiber IO Industry-Pack, a new high-speed fiber-optic communication system which transfers data from node to node at speeds as fast as 10.6 megabytes per second.

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The Power 4e by VI Computers in Encinitas, Calif., is a PowerPC 604e-based VME single board computer with an estimated performance of 6.sspecint95 and 6.1 specfp95.

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Officials at Dynatem in Mission Viejo, Calif., are porting the QNX real-time operating system to their VMEbus-based PC card, the DPCI.

Force develops hybrid VME/CompactPCI system

Engineers at Force Computers in San Jose, Calif., have developed the Pentura VME5-9700, a hybrid CompactPCI and VME system in a rack-mountable 19-inch chassis.

The product enables designers to take advantage of the benefits of VME and CompactPCI in the same box. VME is tough, proven technology that enables designers to place more cards in the backplane than CompactPCI. Yet CompactPCI offers the high-bandwidth, plug-and-play features, ease-of-use, graphical interface and network functionality of Windows NT.

The large number of rear I/O pins (as many as 415) in CompactPCI enables designers to use this approach to bridge to other bus architectures such as STD and VMEbus. Force officials have submitted a specification to the PCI Industrial computer Manufacturers Group (PICMG) in Wakefield, Mass., for a CompactPCI-to-VMEbus bridge that uses 180 of the pins on J4 and J5 as a VME64 bridge.

The Pentura puts to use the durability of Eurocard packaging and its rugged pin-and-socket connectors. The packaging enables it to stand up to environmental factors like shock, vibration, and dust.

It uses an Intel Pentium microprocessor running at 166 MHz, and its system architecture and plug-and-play BIOS ensure 100 percent compatibility with all standard PC software. The platform has four 3U and one 6U CompactPCI board slots, which move data as fast as 132 megabytes per second. It is also designed with five VME64x board slots to support additional I/O for legacy applications.

The platform also has one PCMCIA and one PMC slot. The standard configuration for the system includes 512 kilobytes of L2 synchronous burst cache, 32 megabytes of EDO DRAM with ECC protection, 2 gigabytes hard disk, 8x CD-ROM drive, and two additional mass-storage expansion bays.

The hybrid system is an appropriate option to add high-speed, multi-media, networking, and disk access to an existing VME application. It also represents a way to port an application from VME to CompactPCI, using the hybrid system as a stepping stone, and to use new applications that require I/O functionality already existing in VME, but not yet available in CompactPCI.

Pentura combines the flexibility of CompactPCI with the rugged reliability of VME, says Wayne Fischer, director of strategic programs at Force. It uses an open, high-performance, off-the-shelf solution for applications such as telecommunications, aerospace, industrial control, and medical imaging.

Pentura offers a selection of I/O boards to add plug-and-play products and can add as many as five CompactPCI cards and five VME boards. This enables designers to build the system in short design times at low costs.

The markets that benefit most from the Pentura system include intelligent peripherals for advanced intelligent networks. Where PCs force-fit into the intelligent network applications, the Pentura is designed for them. It also has uses in computer telephony integration through the use of network connectivity and TAPI support.

Fischer says he believes military designers could get an advantage from Pentura because it could help them switch from VME to CompactPCI - J.M.

Industry experts push VMEbus to 320 byte/s

Scientists at Bustronics Corp. in Fremont, Calif., and Arizona Digital in Scottsdale, Ariz., are using new backplane technology that enables synchronous data transmission to push the speed of the VME64 backplane data bus from its current maximum of 80 megabytes per second to 320 megabytes per second.

"VME320 backplanes possess many advantages over traditional backplanes, are 100 percent backward compatible, and can be manufactured for essentially the same cost," says Drew Berding, president of Arizona Digital. "We anticipate the customer demand will drive the market towards the new VME320 backplanes."

Unlike the extended VME64, the VME320 is compatible with the existing base of VME boards. Plus it is twice as fast and is much easier to use than VME64, says Fred Hirsch, general manager of Bustronic.

The VME320 backplanes have forward and backward compatibility to VME systems, and offer high-speed, reliability, ease of use, and lower cost than other recent approaches to high-performance backplanes, the technology`s backers say.

"Allowing VMEbus systems to quadruple their performance and remain backward compatible to first-generation equipment is a technological milestone," says Ray Alderman, executive director of the VMEbus International Trade Association (VITA) in Scottsdale, Ariz. "Bustronic and Arizona Digital are in good standing with the Gods of Backplane Physics."

Scientists came up with VME320 by looking into VME`s weaknesses, Berding says. "While examining VME`s limitations, I uncovered the roadblocks and then developed the backplane technology that pushes VME to a whole new level," he says.

The technology

"Conventional backplanes are wired from slot to slot so that a given pin in each connector is stitched to the next connector and so on down the backplane until all such pins are connected," Berding explains.

Usually, there is a network of pull-up and pull-down resistors at each end of the bus, which then acts like a transmission line with distributed inductance and capacitance, he says.

Once the boards are plugged in, their additional stub and circuit capacitance makes the bus act as a very low-impedance transmission line with a slow propagation time, he says. The fully loaded impedance can be as low as 25 ohms with end-to-end propagation times as fast as eight nanoseconds for a 21-slot backplane. Fully loaded buses have severe reflections and ringing that limit their speed.

The "termination networks" of pull-up and pull-down resistors do not begin to eliminate reflections because the drivers are unable to function at the low levels of resistance necessary to match the impedances and minimize reflections, he says. Therefore, the only way to reliably use such a backplane is to wait a sufficient amount of time for the multiple reflections to die down before using the signal. "This is extremely slow and hurts performance," Berding explains.

The internal construction of the VME320 backplane is very different, he says. Instead of stitching slot 1 to 2, then 2 to 3, etc., the VME320 runs a signal trace from slot 1 to slot 11, a separate trace from slot 2 to slot 11, etc., until all slots have been wired to the common point at slot 11. Therefore all of the trace capacitance, the stub capacitance, and the circuit capacitance appear to be concentrated at slot 11 rather than distributed as in the conventional backplane.

The result: the equivalent circuit of the backplane is a simple lumped 200 pf capacitance - not a transmission line. When the circuit cards are added , the equivalent circuit does not change. It just looks like a larger lumped capacitance.

"Because the backplane acts as a lumped capacitance, the rise times and fall times of the signals are very clean and monotonic - that is, they transition through the switching threshold without hanging or changing direction," Berding says. "This allows a much faster signaling protocol to be used such as SST [Source Synchronous Transfer]. Propagation time does not affect the speed at which data can be streamed. Only the skew on the data and Strobe affect the transfer speed."

In traditional backplanes, the variables affecting backplane signal integrity are the stub length and the transceiver capacitance of each circuit card, while in VME320 backplanes, stub length and circuit capacitance are relatively unimportant; they merely affect the signal rise and fall times but not the signal integrity, he explains.

"The VME320 uses the same 330 ohm pull-up and 470 ohm pull-down resistor networks as standard VME in order to be fully compatible with legacy VME circuit boards," Berding says. "The conventional boards can be operated in VME320 backplanes just as they were in traditional backplanes, the only difference being the signals are cleaner and quieter in VME320 backplanes."

VME320 backplanes are extremely quiet and produce very little cross-talk due to their appearance as a lumped capacitance rather than a transmission line; its rise and fall times are very slow, Berding says. Cross-talk is inversely proportional to signal rise or fall times, which in traditional backplanes are relatively fast.

The VME320 backplane is an ideal candidate for hot swapping circuit boards, as any insertion noise is effectively bypassed by the lumped capacitance equivalent of the backplane, he adds.

Designers of military systems - particularly those who are involved in avionics designs - also are showing interest in VME320, yet are not willing to lend their wholehearted support. Military advocates want further demonstrations that this new technology not only will work as promised but will also provide the reliability and long-term logistics support that military operators need .

VME board suppliers such as DY4 Systems Inc. in Kanata, Ontario, Themis Computer of Fremont, Calif., and CSPI in Billerica, Mass., are expressing guarded interest in VME320, but are waiting to see how the new technology progresses before committing to it. - J.M.

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