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A Faster Chip

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PCQ Bureau
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The structure across the top is an 8 kB data cache, and the structure across the bottom is an 8 kB instruction cache. The right hand side is the floating-point unit. This chip is (1.39x1.68) cm and contained 1.68 million transistors. It was built with 0.75-micron lithography, and had three metal layersIf you’ve shopped at

amazon.com, searched for information on AltaVista, or seen any of Hollywood’s special effects blockbusters like Titanic, chances are you’ve seen the power of the 64-bit Alpha in action.



Alpha architecture was one of the path-breaking developments in the evolution of computing. Let’s see how the Alpha processor has developed over this period.

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1992: The Alpha architecture,

and the first Alpha processor



Digital’s Alpha architecture, announced in 1992, was the first true 64-bit architecture. It was designed for a lifespan of 15 to 25 years, and aimed to replace Digital’s VAX, which had dominated the minicomputer and server markets during the 1980s. Along the way, the Alpha was also expected to challenge Intel’s hold on the CPU market. The Alpha was a clean, pure RISC architecture designed to accommodate a thousand-fold increase in performance over its lifetime (10- fold by clock rate, 10-fold by superscalar execution, and 10-fold by multiprocessing). 

At the launch of the Alpha architecture, DEC also announced the first Alpha implementation–the 21064 CPU. It initially ran at a speed of 200 MHz, and had incredible clock speeds and benchmark performances for that period. This microprocessor was proclaimed to be “The fastest microprocessor on the planet” in 1992, by none other than the Guinness Book of Records.

February 1995: The 21164



In February 1995, DEC introduced the second generation of the Alpha chip–the 21164, which provided peak processing power of more than one billion instructions per second. The chip was the industry’s first to operate at 300 MHz–roughly twice the speed of competing processors–and introduced the idea of level 2 cache on the chip. Faster versions of the 21164–the 433 MHz and 500 MHz–were announced in July 1996, further strengthening Digital’s four-year claim to the world’s fastest and highest-performing microprocessors.

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February 1998: The 21264



The third generation of the Alpha family–the 21264–was introduced in February 1998. With its lethal combination of high-bandwidth buses and micro-architectural innovations, the chip is expected to break the once unheard-of gigahertz barrier by next year. 

This one contained 9.3 million transistors, and introduced the idea of level 2 cache on the chip. It was built with 0.5-micron lithography, and had four metal layersMeanwhile, Digital and Intel got involved in lawsuits and counter-lawsuits about microprocessor patents. These were finally settled with Digital selling its processor fabs to Intel, while retaining the Alpha design. The idea was to continue designing the chips, while getting them fabricated by Intel and Samsung. Along the way, Digital was bought out by Compaq–and the processor became the Compaq Alpha from the Digital Alpha. Compaq plans to develop the Alpha further. Currently, the Alpha’s used in middle and high-end Compaq servers, and Compaq is also in the process of replacing the MIPS processors in its Tandem servers with the Alpha. 

As for the processor taking on Intel, that never happened. For one, it was priced way above Intel’s chips. For another, Windows never ran on it. The Win NT server did for some time, before Microsoft stopped supporting the platform. And in all probability, Digital, and now Compaq, want the chip to operate only in the high-end server market.

The next generation of the Alpha family–the 21364, is expected to be ready by 2000. This chip will operate at speeds greater than 1,200 MHz. 

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