I ran my own blog from November 2006 till October 2014. All posts are still online, but I don't have time to update it anymore. Please note that all images and media files have been removed when the backup was moved to a new host in early 2016. Enjoy!
The DEC Alpha AXP once was the fastest microprocessor in the world, and DEC even managed to keep the Alpha architecture on the pole position for many years, until the Alpha processor project was terminated by Compaq (who had acquired DEC in 1998). So here's the story of the once so powerful AXP architecture.
In the 1980s DEC (or "Digital Equipment Corporation"), who was the maker of the famous VAX mainframe computers, was looking for a successor for their 32-bit VAX processors. DEC was already working on a RISC project called "PRISM", and they were also producing workstations based on the popular MIPS RISC processors.
The 32 bit PRISM processor offered a user-programmable microcode known as Epicode, and it was planned to release it along with a new operating system (codenamed "Emerald") that would be able to run existing VMS programs. In 1988 the PRISM project was cancelled as VAX computers were still selling and the management thought that VAX still had a bright future.
But they were wrong. In the late 1980s and early 1990s RISC processors made huge progresses, and soon the most popular RISC architectures such as MIPS and SPARC offered better price/performance ratio than the traditional VAX systems. It was obvious that the next generation RISC computer systems would completely outperform the VAX.
The DEC management finally changed their strategy and decided to create a RISC processor that would allow running the VMS system dircetly (instead of the Emerald project which only planned some kind of a VMS emulation). The new architecture, designed by Dick Sites and Rich Witek, was basically an improved PRISM including Epicode, but it was also a real 64 bit processor and changes were made to allow running VMS.
While most processor manufacturers were using software programs to layout the processor circuits, DEC decided to design large parts of the CPU circuits by hand. Manual circuit design allowed to better prevent "hot spots" on the chip core, which finally allowed the Alpha to run at much faster frequencies than other RISC processors and to become the fastest CPU in the world.
The first Alpha AXP processor was the 21064. It's internal codename was EV4 ("Extended VAX 4"), when it was released in 1992 it was the fasted RISC chip on the market, it was running at 200 MHz and it was even able to rival minicomputers and mainframes. In fact it was so powerful that many experts believed this processor would dominate the chip market for the upcoming 25 years.
The second generation Alpha 21164 (EV5) was the first microprocessor to place a large secondary cache on chip in 1995. The initial version was running at 333 Mhz, faster versions followed in 1996 (500 Mhz) and 1998 (666 Mhz).
The 21264 (EV6) introduced a more sophisticated out-of-order execution microarchitecture, the 450 Mhz version was released in 1998. Faster versions following within the next few years, reaching an incredible 1. 25 GHz in 2001.
In 1998 DEC was acquired by Compaq, who instantly decided to phase out the Alpha project in favor of the announed Intel IA-64 architecture. Production of the Alpha continued to support customer needs, and the upcoming EV7 design was being completed, but all futher projects were halted. In 2001 Compaq was acquired by Hewlett Packard (Intel's IA-64 partner) and the Alpha intellectual property was finally sold to Intel.
During the time Compaq, Hewlett Packard and Intel decided to kill the project the Alpha AXP was still the fastest CPU available, and the two fastest supercomputers in the US were powered by Alpha processors (shame on you!!!)
The last Alpha was the 21364 (EV7), which included an Integrated Memory Controller and featured four 1. 6 Gbyte/s inter-processor communication links for improved multiprocessor system performance. It was released in 2003 and was running at 1 or 1. 15 GHz. Compaq continued selling Alpha solutions until April 2007 to fulfill the needs of the existing customer base. The last Alpha EV7 versions were running at clock speeds of up to 1. 3 Ghz. On April 27, 2007, HP stopped selling AlphaServers.
The EV8 was never released, it would have been the first Alpha to include simultaneous multithreading. It is rumored that Intel's current Xeon Hyperthreading architecture is mainly based on Alpha technology. The planned EV9 (codenamed "Tarantula") was planned to include a powerful vector core, but this project was terminated long before it could have resulted in a real product.