Sun rises to the challenge

DN Staff

February 19, 1996

9 Min Read
Sun rises to the challenge

Menlo Park, CA--In the fall of 1991, when a $12,000 SPARCstation offered perhaps one-tenth the power of today's high-end PCs, several Sun Microsystems executives went off to Aspen to plot the company's technology future.

"We knew we were going to have to have a new generation of machines after SuperSPARC," recalls Ken Okin, vice president of desktop engineering. "We literally went up a mountain and hashed out the innards of UltraSPARC" -- how fast the machines should run (about four times the speed of existing systems), and the new technologies they needed to develop.

The result: a new generation of 64-bit machines with a huge leap in performance, including 100-Mbits/sec networking and up to 505 SPECfp92 (more than double the floating-point performance of a 150-MHz Pentium Pro). Early reviews from power-hungry users are positive. "People are waiting in line to use Sun's systems," reports John Zepper at Sandia National Laboratories.

In order to make UltraComputing a reality, engineers would struggle with how to dramatically increase the speed of information flowing through the system, how to make a quantum leap in graphics performance, and how to cram as many electronics as they needed into available space. "I have quite a few gray hairs from this one," laughs Les Poltrak, group manager of Advanced Desktop Systems at Sun Micro-systems Computer Co.

High-tech crystal balls. Predicting future market demand is always a dicey business. But it's especially tricky in the computer industry, where products can become obsolete in months. Here, long-range planning means betting on when technologies in their infancies will be ready for full-volume production. One high-stakes gamble: counting on fledgling ball-grid-array (BGA) packaging technology--common today, but new back in '92--to stuff enough circuitry onto printed-circuit boards. "We drove that industry," says Todd Lynch, director of desktop engineering.

Engineers also decided to use 100-Mbit/sec Ethernet networking in the machines, a ten-fold speed increase from existing conventions. It was a wise move, with the subsequent explosion in network traffic, driven by the World Wide Web and huge CAD files.

For Sun, the four-year Ultra project looked increasingly urgent as analysts began criticizing the company for lagging behind competitors in power and graphics capabilities. "Everybody knew the future of the company depended on this," Lynch says.

But the program's importance carried a big upside as well. Team members said they had no problem getting the manpower, money, and other resources necessary to do the job. An estimated 800 people worked on Ultra development, with access to a network of 600 computers working just to design the UltraSPARC processor alone.

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To make the leap to Ultra, engineers knew they needed more than a faster processor. After a year of examining various alternatives, they decided to ditch conventional bus technology in favor of a packet-switch cross-bar interconnect.

A system bus allows one data transaction at a time. The new interconnect, however, has 3 paths in and out. Engineers liken it to the difference between a telephone party line--where only one conversation can occur at any given time--and more modern phone networks that handle multiple calls. Such packet-switch interconnects have been used before on high-end systems; Texas Instruments engineers working to Sun specifications streamlined the concept to three channels and brought it down to the desktop.

Engineers also faced the challenge of designing pcbs using BGA technology, which offers very dense numbers of interconnects on a grid, not merely a perimeter. Thus, designers could pack 700 components on a board's bottom, and 1,300 on top. "We had to define and engineer routing rules which didn't exist before," says Brian Verstegen, electrical system manager. "We had special test boards done in manufacturing to qualify the process." The Ultra design would have been impossible without BGA, he says.

Three-dimensional modeling proved crucial to design packaging with the new technology, says board designer Eric Selna. "We weren't waiting for prototypes to find out if it worked."

Testing procedures also changed to meet project demands. Time and cost pressures precluded the company's typical assembly procedures that tested systems at various stages in huge walk-in ovens. Instead, engineers designed-in the capacity to vary operating frequencies for testing, which mimics stresses in the ovens. "We found smarter ways to get the job done," he says.

From theory to products. Once the broad technological outline of Ultra architecture was in place, engineers turned to creating real-world products from the broad design. The initial plan was to design an "Ultra 1'' workstation using an existing 3-inch enclosure -- a demanding task.

"The power supply was threatening to block air flow through the box, due to the high power delivery needed--180W--shoehorned into the space originally intended for a 100W power supply," explains Lee Winick, mechanical project lead engineer for the Ultra 1. "This would mean restricted airflow, expensive (miniaturized) components, high fan rpm, etc." But company officials were not keen on modifying the well-known 3-inch Sun "pizza-box" form.

"By around July last year, we realized that it wasn't going to work," recalls Dimitry Struve, manager of enclosure engineering for desktop systems. "The clock was ticking. And the thought of starting something new was intimidating." Especially since the initial 18-month project had called for simple modifications of an existing chassis; with eight months already gone, the team had to begin from ground zero.

The new plan added another inch of height to the box--and then the team had 10 months to create the new system. A major issue: cooling. Engineers had to grapple with a 40W central-processing cluster, at a time when the then-new Pentium--at much less power--was challenging engineers elsewhere.

While initially considering some exotic cooling schemes, Sun engineers ended up using TCM (Thermal Cooling Module) fans mounted on a heat sink.

In the Ultra 1, an impingement fan blows turbulent air directly on the processor. Bulkflow fans in the power supply evacuate the main CPU cavity, while a front fan spot-cools system drives. The high-end, upgradable Ultra 2 features two additional fans. "Cooling it quietly was the hardest thing to do," says Vince Hileman, mechanical project lead for the Ultra 2.

New ways to collaborate. How to keep team members informed of daily progress and changes in critical data? Winick turned to today's hot Internet technology for in-house use, and created an internal World Wide Web-like site for all project engineers to access.

The move was a departure at Sun, where corporate culture revolves around e-mail and engineers are used to being deluged with hundreds of messages daily. Instead, the onus was on team members to remember to sign in and check for info updates. "It requires people to get engaged in the project, because you're not pushing the data out," Struve notes.

Along with the major issues in designing a product with new technology, engineers also had to tend to the typical details surrounding any system. In one case, the team decided to replace Sun's proprietary mini-connectors for peripherals with industry-standard connectors. That made customers happier, but also caused designers to scramble to find usable space.

Increasing the board size would have raised costs unacceptably, because the existing dimensions just allowed them to create four boards per panel of raw material; a larger board would have cut that to two boards per panel, causing large-scale waste. One solution was re-using a card-edge connector designed for system testing; it's now also the internal SCSI port, eliminating an extra connector and the board area needed to mount it.

Engineers tested system designs using special "thermal dies" --chips that can accurately measure junction temperatures to look for potential hot spots. Despite the heavy use of computer simulation tools, Struve notes, "there was a lot more experimental work than you might expect." Engineers also developed a number of rapid-prototype models.

Prototypes are typically used to validate designs before moving on to production, but the Sun team shaved a week off development time by releasing tooling and rapid-prototype data simultaneously. Since it took just a few days to get the models back, Winick explains, tooling instructions could be easily changed if the prototypes showed a problem.

"We wound up with final-tooled production quality much earlier in the qualification process," he says. "That requires a big push in the front end of the project to release that tooling; but reduces effort and risk, and increases confidence at the back end--a welcome tradeoff." Sun also eliminated the typical Urethane cosmetic plastics cycle, which more than paid for residual tool modifications.

Sun engineers found themselves working closely with chassis suppliers in the U.K., power-supply makers in Austria and Japan, and other suppliers around the globe. "Our suppliers were part of the design process from day one," Hassan Siahpolo, operations mechanical engineer for the Ultra 1, declares. For British suppliers used to being a second source for mature designs, it was a new experience.

As product launch neared, engineers scrambled through the night in order to claim the fastest desktop workstation in the industry. Doubling system cache and running the CPU at 200 MHz still left them just shy of Digital Equipment's latest Alpha workstations, Lynch says -- until they turned to a parallelizing compiler to further boost performance and claim they finally edged ahead.

Not all industry analysts agree that the Ultra 2 actually outperforms DEC's Alpha in real-world applications. And, several note, leapfrogging is likely as other computermakers announce their next-generation products. But, industry watchers agree that Ultra allowed Sun to jump back into the desktop-technology race--at very aggressive prices. And for Sun users, Ultra can offer double or more the performance of older SPARCstations on engineering tasks using software such as Parametric Technology's Pro/ENGINEER.

The Ultra roll-out was the most lavish--and expensive--in Sun history. "When some of us saw the announcement, the presentation, we thought, 'wow, this is really hot stuff,''' Struve laughs.

"The bottom line is, it's very good news for Sun," says Andy Feit, an analyst with Dataquest. "They went from being very weak on technology to very much back in the game. It's well designed, and they built it to be manufacturable in volume--at prices people are willing to pay."

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