The DEC Alpha reference article from the English Wikipedia on 24-Jul-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

DEC Alpha

The DEC Alpha, also known as the Alpha AXP, is a 64-bit RISC microprocessor originally developed and fabricated by Digital Equipment Corp. (DEC), who used it in their own line of workstations and servers. Designed as a successor to the VAX line of computers, it supported the VMS operating system, as well as the DEC flavour of UNIX. Later open source operating systems also ran on the Alpha, notably Linux and certain BSD UNIX flavours. Microsoft supported the processor until Windows NT 4.0 SP6 and did not extend Alpha support to Windows 2000.

Alpha was born out of an earlier failed RISC project named PRISM. That earlier architecture was killed by the popularity of Digital's own VAX computer line. The executive staff couldn't see the need to replace their cash cow at the time. Another problem was that PRISM was to have a totally new operating system called Emerald which was not compatible with the older VMS OS and the full software suite would not be ready for some time. Eventually some of the company engineers saw that other RISC architectures, such as SPARC and MIPS, were offering much better price/performance then the VAX lineup. So a study was started to see if a new RISC architecture could be defined to support the VMS operating system. Eventually that new architecture became Alpha.

The Alpha 21064 was introduced in 1992 running at 200MHz (the Intel Pentium, in comparison, ran at 66MHz when it was launched the following spring). The 64-bit processor was a superpipelined and superscalar design. At the time, DEC touted it as the world's fastest processor. In July 1996 it was clocked at 500 MHz (the 21164PC), in March 1998 at 666 MHz and in May 2000 at 731MHz (the 21264). 1GHz and faster pieces were announced in 2001 (the 21364 or EV7), and are available since 2003 at 1.1GHz+. Around 500,000 Alpha based systems were sold to end-2000.

The first few generations of the Alpha chips were some of the most innovative of their time. The first device, 21064 or EV4, was the first CMOS microprocessor whose operating frequency rivalled higher-powered ECL minicomputers and mainframes. The second device, 21164 or EV5, was the first microprocessor to place a large secondary cache on chip. The third device, 21264 or EV6, was the first microprocessor to combine both high operating frequency and the more complicated out-of-order execution microarchitecture.

The main contribution of Alpha to the microprocessor industry was not so much the architecture but rather the superb implementations. At that time (as it is now), the microchip industry was dominated by automated logic synthesis driven design flows. The chip designers at Digital continued pursuing sophisticated circuit design in order to deal with the overly complex VAX architecture. The Alpha chips showed that custom (eg. human) circuit design styles when applied to a simpler, cleaner architecture allowed for much higher operating frequencies then that were possible with the more automated design flows. These chips caused a renaissance of custom circuit design within the microprocessor design community. The Alpha instruction set architecture is somewhat of a evolutionary improvement from the MIPS architecture.

The production of Alpha chips was licensed to Samsung Electronics Company. Following the purchase of Digital by Compaq the majority of the Alpha products were placed with API NetWorks, Inc. (previously Alpha Processor Inc.), a private company funded by Samsung and Compaq. In October 2001 Microway became the exclusive sales and service provider of API NetWorks' Alpha-based product line.

Compaq announced that computers using Alpha would be phased out by 2004 in favour of Intel's Itanium. HP, new owner of Compaq, announced that support the Alpha series would continue even for a few more years, including the release of the EV7z chip, but this will be the final iteration of the chip. The IA-64 is supposed to be the replacement of this series.

Ironically, in mid-2003, as the Alpha were about to be phased out, the fastest computer in the U.S, and second fastest in the world, was a cluster of 4096 Alpha processors.

A persistent report attributed to DEC insiders suggests the choice of the AXP tag for the processor was made by DEC's legal department, who were still smarting from the VAX trademark fiasco. After a lengthy search the tag AXP was found to be entirely unencumbered. Within the computer industry, a joke got started that the acronym AXP meant Almost Exactly PRISM.

Model History

Model	AKA	Year	Frequency [Mhz]	Process [µm]	Transistors [millions]	Die size [mm²]	Pins	Power [W]	Voltage	Mem [MB/s]	Dcache [k]	Icache [k]	Scache	Bcache	ISA
EV4	21064		100-200	0.75						80	8	8
EV45	21064A									80	16	16
EV5	21164	1995	366-500	0.5	9.7	49?	296	56	3.3/2.5	150	8	8	96k	1	R
EV56	21164A	1996	400-767	0.35				54		300	8	8	96k	1-2M	R,B
PCA56	21164PC	1997	400-533	0.35	3.5	141	264	32	3.3/2.5		8	16
1M	R,B,M
PCA57			600-666	0.28	5.7	101	283	20	2.5/2.0		16	16
1M	R,B,M
EV6	21264	1998	450-600	0.35	15.9	314		73		1600	64	64
2-8M	R,B,M,F
EV67	21264A	1999	667-750	0.25	15.9	210					64	64
2-8M	R,B,M,F,C
EV68AL	21264B	2001	800-833	0.18	15.9	125					64	64
2-8M	R,B,M,F,C,T
EV68CB	21264C										64	64
2-8M	R,B,M,F,C,T
EV68CX	21264D										64	64
2-8M	R,B,M,F,C,T
EV7	21364	2003	800-	0.18							64	64	1.75M
R,B,M,F,C,T