The Alpha Alternative

Michael Slater

For the performance-driven user, Digital Equipment Corp.'s Alpha architecture offers an interesting alternative. The Alphas are the fastest of all the RISC processors and the only ones for which Microsoft Windows NT support has been maintained (NT support for MIPS and PowerPC was dropped last year). If your productivity is limited by the performance of one or two high-end applications, and those applications are available for Alpha, then an Alpha system may be a good choice.

Today's Alpha processor is the 21164, which Digital offers at clock speeds from 300 to 600 MHz. On integer applications, the performance increase over Intel's Pentium II is not as great as the clock rate advantage suggests; while the clock speed is high, the amount of work done in each clock cycle is lower. The actual performance advantage varies greatly depending on the application. For floating-point applications such as 3-D graphics and computer-aided design, the 21164 is a stellar performer.

Technically, the 9.6-million-transistor 21164 is an impressive design. It has 16K of on-chip Level 1 cache plus 96K of on-chip Level 2 cache. The system bus is 128 bits wide, enabling it to deliver much higher bandwidth than the 64-bit bus in x86-based systems.

The challenge all RISC processors have faced in attacking the PC market is a lack of application software. Digital has aggressively pursued software developers and has assembled an impressive catalog of applications, but they tend to be in the engineering and authoring areas--not mainstream PC applications.

To address this problem, Digital has developed an interesting software product, called FX!32, that enables the Alpha to run nearly all 32-bit x86 Windows applications. Performance is much better than with other software emulators, such as SoftPC, but is only about 50 to 70 percent of that of native Alpha code (according to Digital). FX!32 is a good way to get access to a more complete suite of applications--it may save you from needing an x86 PC in addition to an Alpha system--but it is unlikely to deliver leadership performance or value.

Most Alpha systems are far more expensive than typical PCs. Digital is sampling a new processor, called the 21164PC, that is less expensive than the original 21164 yet delivers nearly as much performance. It will be offered at clock speeds of 400, 466, and 533 MHz. Prices for the new processor are expected to be about $495 (533 MHz) in quantities of a thousand, compared with $1,450 for the 500-MHz 21164 or with Intel's Pentium MMX, for example, priced at $386 for the 233-MHz part.

Digital expects systems using this chip to appear by the end of this year, at prices as low as $2,500. With these lower-cost systems, Alpha will be able to address more of the PC market--if there are enough native applications to lure users.

Next year, Digital plans to begin shipping the 21264, which should leave even Intel's best x86 processor in the dust, especially in FP performance. Until 1999 or later, however, systems using this chip are likely to be priced above $10,000--often way above. If price is no object and you want the world's fastest Windows NT system, this is the processor to watch for.

From the September 23, 1997 issue of PC Magazine

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