By John Keller
SAN JOSE, Calif. - Engineers from Force Computers Inc. are rolling out what they claim is the industry`s first marketable implementation of 2e VME, which boosts backplane throughput from the current 80 megabytes per second to a theoretical maximum of 160 megabytes per second.
The Force offering, the SPARC CPU-20VTe single-board computer, is widely expected to usher in a new generation of fast VMEbus products that will begin with the 160-megabyte-per-second 2e VME in the near term, and lead up to VME 320 products with backplane bandwidths reaching 320 megabytes per second by 1998.
"People have always wanted additional backplane speed," says John Rynearson, technical director of the VME Industry Trade Association (VITA) in Scottsdale, Ariz. "If you can move data faster on the backplane you can do applications anywhere you can shovel data quickly, particularly in the imaging area, DSP applications, and those kinds of things."
The Force CPU-20VTe operates at 110 megabytes per second on the VMEbus, according to Force officials. With today`s technology, reaching the theoretical maximum of 160 megabytes per second on 2e VME is difficult because "silicon only goes so fast," Rynearson says. "When you sit down and look at a complex design, you find there are delays. The bottlenecks are in the timing circuits and in terms of mechanical tolerances."
While Force designers are using a company-designed ASIC to implement the 2e VME protocols, officials at Tundra Semiconductor in Kanata, Ontario, are making ready to offer interface silicon over the next several
months. Tundra leaders also have voiced a commitment to provide interface silicon for VME 320.
Marketers at Force gauge substantial interest in the 2e VME product from military and aerospace designers, says Mark Pittman, group manger of product marketing at Force. "It`s a bandwidth-hungry world," he says. "In potential military applications we have radar and mission planning where this would be used."
The 2e VME protocol, set for balloting as an official VITA standard this month, increases available VMEbus bandwidth by reducing the number of handshake signals per transfer from four to two. This reduction in bandwidth for protocol management goes to data transfer and effectively doubles bus throughput.
While the bandwidth increase of 2e VME comes from software enhancement in the protocols, the much faster VME 320 achieves its bandwith from enhanced electrical characteristics of the bus design, industry experts say.
Other companies in the VME board business are gearing up for the improvements that 2e VME and VME 320 offer. "We will do VME 320 and 2e VME over the next year. We view them as two enabling technologies," says Douglas Patterson, technical marketing manager for DY 4 Systems in Warrenton, Va.
"It is safe to say we see a number of the vetronics programs taking advantage of both, not in the machine-control area, but more in the sensor area," Patterson explains. "And in avionics community people have been asking a lot of questions."
Patterson says 2e VME and especially VME 320 will give designers a funda- mentally new way to plan for data communications. "Generally people use VME for control and a high-speed serial data bus for data," he says. "You can now pass live video down the VME bus, and still have plenty of bandwith to pass control and to do other things. It is a fast wide pipe."
