Chip giants go their own ways (Part 2)

Continued from part 1

AMD argues that Intel's approach reinvents the wheel. The chip maker this week made public an aggressive plan to follow Intel into the 64-bit processor market in 2001.

AMD is focusing on delivering a 64-bit processor on a modified version of the existing x86 instruction set for desktop processors. AMD calls the new architecture x86-64. "We've extended the x86 instruction set in a fully compatible fashion, to 64-bits" said Fred Weber, vice president of engineering for AMD's Computational Products Group. "It allows us to leverage all the existing design technologies and the software community to leverage (existing) tools and knowledge."

The majority of users, however, won't need 64-bit processors to obtain good performance on common desktop applications such as word processing or even image-editing software, Weber said. "A lot of our strategy is based on that fact. Our strategy explicitly keeps x86 as a first-class citizen," he said.

The rival Itanium chip from Intel will be 64-bit, but it will also include 32-bit "emulation" for non-64-bit optimised applications. It is unlikely that software developers will port desktop applications to 64-bits, because there is little performance advantage to doing so. But attendees at this week's Microprocessor Forum wanted to know if the Pentium III chip and other 32-bit processors from Intel will out-perform Itanium in its 32-bit mode. "Will Coppermine (the cutting-edge process technology for Intel's latest Pentiums) be faster or slower than 32-bit emulation on (Itanium)?" asked one attendee during a Q&A session Tuesday. Intel executive Jim Wilson, who managed the design of the 0.18 micron Pentium III chip responded, "They're two very different parts and two very different markets."

The question hit a chord with developers, who will have to maintain two code bases, a 32-bit and a 64-bit version, in order to support Itanium. At the same time, it bolsters AMD's strategy. "If you need something, add it," said AMD's Weber, referring to Intel's effort to push a brand new processor instruction set, which will require software developers to port compilers, operating systems and applications to its 64-bit Itanium platform.

AMD says that developers will need to do work to optimise for x86-64, but that their software, including operating systems, compilers and applications optimised for 64 bits, will work equally as well on its 32-bit chips. AMD will "innovate under the covers so that the software community doesn't have to change what it's doing," Weber said.

Single-chip multi-processing The company plans to work with operating system and compiler vendors, over a process of several steps, to help them port their wares to its x86-64 processor. The first such x86-64 processor, code-named Sledgehammer, will be based roughly on the processor core design of AMD's Athlon chip. The current Athlon core is 64-bit capable, but the company needs to increase its input output capacity to make 64-bit addressing possible, AMD officials said.

Additional work will be done with the chip to make it possible to put two of the processors on a single chip. This work will include developing each chip to be smaller and more power efficient in order to fit two on the same die. The work AMD does on 64-bit will be passed on to its 32-bit processors as well. It is possible that AMD might utilise the experience gained from developing its first x86-64 chip to deliver a single-chip multi-processor for desktops.

"This is a way to significantly heighten performance in servers and will be a great boon for the desktop," Weber said. Single-chip multi-processing is an approach that has also been adopted by IBM's Power4 processor, a server chip based on the company's PowerPC design. Intel has not yet disclosed plans any plans to deliver a CMP Itanium chip.

part 1

Part 3