The new 500MHz Alpha 21164
In early July this year,
Digital announced the next level of its high-end Alpha CPUs: 433, 466, and
500MHz versions of the 21164A (revision EV5). These Alpha CPUs are all built
from a 0.35µm CMOS process. Subtle changes (over the previous release of
the chip) to the pipeline architecture and word addressing scheme enhance
performance. The 433MHz chips have been available for a couple of months, and by
the time you read this article, Digital will be shipping the 500MHz chips in
quantity. The 466MHz version offers systems vendors an opportunity to see how
the 500 will perform. The 466MHz chip probably will not show up in many
production computers because accommodating the faster CPU is just a matter of
changing the clock frequency of the motherboard.
As with the original release of the 21164, this release is still a fully
pipelined 64-bit architecture, but with a smaller device size, lower core
voltage (2.2V), and higher operating speedthe chip will still dissipate
only 22 watts of power at 366MHz. All other characteristics, such as its onboard
96KB Level 2 cache, 8KB/8KB instruction and data Level 1 cache, and superscalar
instruction handling (four instructions retired per clock cycle), remain
unchanged. The 500MHz chip is the latest in a string of updates over the past
nine 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, Digital
plans to release lower-priced systems based on a new version of the 21064A (such
as the 21164PC). Digital will manufacture this system jointly with Mitsubishi
and market to a new entry-level graphics PC market. In mid-1997, Digital
Semiconductor will release the 21264, an entirely new architecture that will far
exceed the performance of the current CPU generation and break the 500MHz speed
barrier. Following the 21264, Digital will add motion video instructions to the
Alpha architecture to make it a bigger contender in the multimedia market as a
high-performance system that won't need any costly peripheral cards. As Digital
releases each new generation of chip, the company will drop the price points of
the previous versions. Over the next three years, system prices will drop to
below $3000.
In the Windows NT Magazine Lab, the new 500MHz 21164 performed at
twice the speed of the earlier 300MHz 21164 (EV4). With LightWave 3D on a system
with the new DEC AlphaPC 164 Motherboard and running against a Deskstation
Raptor 3, the new Alpha chip cut render times in half. With end-user system
prices 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-bit
version of Windows NT (most likely, NT 5.0). Aimed at enterprise applications
that need to access extremely large databases, such as applications for credit
card companies or airlines, the new 64-bit very large memory (VLM) architecture
will 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-bit
engine, instead of a 64-bit chip squeezed onto a 32-bit bus. MS BackOffice will
be among the first applications ported to this new environment.