Advanced Micro Devices's next-generation K7 processor will be "mechanically interchangeable" with Intel's Pentium II cartridges, but that will not mean the two chips can run on the same boards, according to officials.
Although AMD plans in 1999 to ship the K7 in a cartridge package that will fit into the same Slot 1 interface as Intel's Pentium II, the circuitry inside AMD's cartridge will be different, says David Somo, AMD-K6 divison marketing manager at the Sunnyvale, California-based chip vendor. The result is that motherboards will need to be built around different core logic chips than Pentium II boards.
One major difference between the two processor offerings will be the bus infrastructure. While both the Pentium II and K7 cartridges feature a built-in direct bus between the CPU core and Level 2 cache memory, AMD's cartridge will use the EV6 bus design that Digital uses for its Alpha processors.
"It will not be compatible" with the Intel bus design which the chip giant has not made available for anybody else, says Somo.
"There has been a lot of confusion about this mechanical compatibility since Jerry Sanders' presentation at the Microprocessor Forum," says Somo, referring to AMD's chairman and CEO who first discussed the K7 earlier this month.
But by retaining mechanical compatibility, AMD still counts on reaping some benefits from the Intel infrastructure.
The physical size and designs can be same, which means that it will still be cheaper for AMD's partners to manufacture motherboards and system chassis for K7 PCs than to come up with completely new designs, says Somo.
"That's the kind of compromise you need to make when you are competing with someone who controls over 80% of the market," he says, referring to Intel's dominant market position.
Officials at several motherboard makers here say that this so-called fragmentation of the hardware infrastructure for x86 PCs is a reality that the industry will have to accept in future.
"Look at the MediaGX boards in those Compaq sub-US$1,000 Presarios and you will see that the MediaGX [processor from Cyrix] is soldered direct onto the board," said one official, asking not to be identified.
Most Pentium-class desktop PC chips, including those from Intel and AMD as well as other Cyrix offerings, fit into a common board interface known as Socket 7, notes the official. And that may be one reason why there are so few suppliers of MediaGX boards, the official adds. "But that's still one of the hottest boxes on the market now, so a different design does not necessarily mean that it won't sell."
AMD can be reached via its World Wide Web site at http://www.amd.com/.