| When you're number four, you try harder — or at least try
something different. That's the idea behind NexGen's
strategy for competing with AMD and Cyrix in the
high-stakes challenge to Intel's domination of
fifth-generation x86 processors. NexGen (Milpitas, CA) was founded in 1986, and until now, it had not sold a single chip. Plagued by engineering problems, NexGen labored for eight years to design a processor that could compete in the big leagues. Now NexGen finds itself ahead of AMD and Cyrix, whose 586-class chips won't appear in systems until 1995. Alaris (Fremont, CA), previously a motherboard manufacturer, introduced the first PCs with NexGen's Nx586 processors in September. Retail prices are about 10 percent less than those for comparable Pentium systems. That's the key to NexGen's strategy: By offering processors that almost exactly match the Pentium's performance at lower prices, it hopes to carve out a niche in the huge x86 market. But the most interesting aspects of this strategy are that NexGen's chips run at unusual clock speeds, and those clock speeds won't be advertised. Instead, NexGen is assigning numerical designations to its chips that relate to the performance of Pentium systems. NexGen's reasoning is that clock speeds are a poor measure of comparative performance — and a measure that will become even poorer as the microarchitectures of x86 chips continue to diverge. This is borne out by benchmark tests and simulations, which show that 586-class processors from AMD, Cyrix, Intel, and NexGen do not necessarily deliver equivalent performance at the same clock speeds. As future designs evolve along different paths, the disparities will become even greater. Of course, clock rates have always been a confusing way to compare CPUs. A 33-MHz 486, for example, easily outruns a 33-MHz 386. But until now, clock speeds were relatively indicative of performance within a particular x86 generation; a 50-MHz 486 does indeed run about twice as fast as a 25-MHz 486. But, because the various fifth-generation x86 microarchitectures radically differ, these shorthand comparisons are less valid than before. NexGen, AMD, and Cyrix all claim their 586-class chips will outperform a Pentium at the same clock. That's why NexGen has decided to deemphasize clock speeds as a marketing tool. The result: a line of four processors, named the Nx586-P100, Nx586-P90, Nx586-P80, and Nx586-P75. By controlling the internal clock with a PLL (phase-locked loop) circuit, the Nx586 chips can operate at virtually any clock speed (within their design limits, of course). Thus, the Nx586-P100 runs at 93 MHz; the P90, at 84 MHz; the P80, at 75 MHz; and the P75, at 70 MHz. NexGen arrived at these odd clocks by running many application-level benchmarks and comparing the results to those of Pentium systems. NexGen says the P100 matches the performance of a 100-MHz Pentium, and the P90 matches that of a 90-MHz Pentium. Because those odd clock speeds are much too fast for economical PC motherboards, the Nx586 chips — like most of Intel's Pentiums — run the CPU bus at a slower pace. Every Nx586 processor has a half-speed bus. Thus, the P100 runs at 93 MHz internally and 46.5 MHz externally; the P75 runs at 75 and 37.5 MHz, respectively. In turn, Alaris motherboards have an oscillator that matches the system clock to the CPU bus. (Alaris systems that have a PCI [Peripheral Component Interconnect] bus always run it asynchronously at its top speed of 33 MHz.) NexGen is pricing its chips far enough below those of Intel's Pentiums so that system vendors can make Nx586-based PCs that sell for hundreds of dollars less than comparable Pentium PCs. An Nx586-P75 system with 8 MB of RAM, a 340-MB hard drive, and a 14-inch color monitor is expected to retail for $1645 to $1850, depending on dealer discounts. A comparable Pentium system would cost more than $2000. Another departure in NexGen's strategy is to play down the importance of floating-point performance. Unlike other 586-class processors, the Nx586 chips do not have an on-board FPU. Originally, NexGen planned to offer a separate FPU, similar to Intel's FPUs for the 286 and 386. Instead, NexGen is working on new versions of its processors that will use the CPU and FPU on a multichip module. These variants are scheduled for production in early 1995. To maintain compatibility with motherboards designed for current Nx586 chips, the multichip module will have the same pin-out. Unfortunately, this means about 100 pins — originally reserved to connect the CPU and FPU — will be redundant, because the two dies will be interfaced on the module. Those useless pins will inflate the cost of the modules. NexGen hopes to eliminate them by introducing a redesigned die later in 1995. By the end of next year, NexGen also promises to debut the Nx686, a sixth-generation processor. NexGen predicts that its performance will be two to four times that of a 586-class chip. Although it took NexGen eight years to finish the Nx586, the company claims it has mastered the art of x86 design and can produce new generations with relatively little effort. But even if that claim seems a trifle optimistic, NexGen definitely has arrived and is a credible contender. Copyright 1994-1998 BYTE |