New Alpha CPU Raises the Bar

The new 500MHz Alpha 21164

In early July this year,Digital announced the next level of its high-end Alpha CPUs: 433, 466, and500MHz versions of the 21164A (revision EV5). These Alpha CPUs are all builtfrom a 0.35µm CMOS process. Subtle changes (over the previous release ofthe chip) to the pipeline architecture and word addressing scheme enhanceperformance. The 433MHz chips have been available for a couple of months, and bythe time you read this article, Digital will be shipping the 500MHz chips inquantity. The 466MHz version offers systems vendors an opportunity to see howthe 500 will perform. The 466MHz chip probably will not show up in manyproduction computers because accommodating the faster CPU is just a matter ofchanging the clock frequency of the motherboard.

As with the original release of the 21164, this release is still a fullypipelined 64-bit architecture, but with a smaller device size, lower corevoltage (2.2V), and higher operating speed­the chip will still dissipateonly 22 watts of power at 366MHz. All other characteristics, such as its onboard96KB Level 2 cache, 8KB/8KB instruction and data Level 1 cache, and superscalarinstruction handling (four instructions retired per clock cycle), remainunchanged. The 500MHz chip is the latest in a string of updates over the pastnine months that took CPUs from the 266MHz 21064 to the 300MHz, 333MHz, 366MHz,and 400MHz 21164. Figure A shows a functional diagram of the 21164.

The future holds several changes for the Alpha line. Currently, Digitalplans to release lower-priced systems based on a new version of the 21064A (suchas the 21164PC). Digital will manufacture this system jointly with Mitsubishiand market to a new entry-level graphics PC market. In mid-1997, DigitalSemiconductor will release the 21264, an entirely new architecture that will farexceed the performance of the current CPU generation and break the 500MHz speedbarrier. Following the 21264, Digital will add motion video instructions to theAlpha architecture to make it a bigger contender in the multimedia market as ahigh-performance system that won't need any costly peripheral cards. As Digitalreleases each new generation of chip, the company will drop the price points ofthe previous versions. Over the next three years, system prices will drop tobelow $3000.

In the Windows NT Magazine Lab, the new 500MHz 21164 performed attwice the speed of the earlier 300MHz 21164 (EV4). With LightWave 3D on a systemwith the new DEC AlphaPC 164 Motherboard and running against a DeskstationRaptor 3, the new Alpha chip cut render times in half. With end-user systemprices running under $10,000, the new Alpha is a real bargain.

One other thing you can look forward to on the Alpha platform is a 64-bitversion of Windows NT (most likely, NT 5.0). Aimed at enterprise applicationsthat need to access extremely large databases, such as applications for creditcard companies or airlines, the new 64-bit very large memory (VLM) architecturewill support almost any sized database mapped directly into addressable memory.Alpha is an ideal CPU to accommodate this task because it is a true 64-bitengine, instead of a 64-bit chip squeezed onto a 32-bit bus. MS BackOffice willbe among the first applications ported to this new environment.