PCI Express Usurps AGP, PCI Standards

SEATTLE -- The next-generation technology that will speed data to components of your next PC--replacing stalwarts such as PCI and AGP--now has a moniker to match its performance: PCI Express.

Developed under the code name 3GIO, the technology comes from the Arapahoe Workgroup team, which unveiled the new name at Microsoft's Windows Engineering Conference here this week. Executives of Compaq, Dell, Hewlett-Packard, IBM, Intel, and Microsoft make up the team.

The group now passes the specification on to the PCI-SIG board of directors. The PCI-SIG is an open industry standards group that manages PCI specifications. The board will offer the specification to its 740 member companies for review before posting an official specification in June. PCI-SIG executives say PCs and hardware using the technology should begin to appear by 2003.

Faster, of Course

PCI Express will offer blazing throughputs of 2.5 gigabits per second. That kind of speed is ideal for next-generation graphics cards, ethernet cards, and other high-speed hardware, say the developers.

Today's aging Peripheral Component Interconnect (PCI) bus typically offers a paltry 128 megabytes per second throughput. Because hardware such as graphics cards have evolved to require faster throughput than PCI could offer, new bus technologies such as the Accelerated Graphics Port (AGP) evolved. PCI Express should help eliminate the need for some hardware-specific buses. That said, CPU, memory, and hard drive-specific buses will remain.

While these components use their own individual buses, the key to continued PC performance gains is to make sure the rest of the system can keep up, says Bob Gregory, Arapahoe Work Group spokesperson.

"We must scale and balance performance" to ensure the components can keep pace with future processors and memory systems, he says. PCI-SIG executives say PCI Express technology can keep up with CPUs running in excess of 10 GHz.

Backward Compatible

Like all good PC industry standards, PC Express is a technological leap forward, but doesn't leave behind existing hardware. The new specification will continue to support today's PCI. In PCs, support will likely appear in the form of both PCI Express and PCI slots.

Like the Industry Standard Architecture (ISA) bus before it, PCI will probably stick around for some time to come, according to Gregory. Some applications just won't migrate [to PCI Express]," he says. "When the last low-volume [product] goes from PCI to PCI Express, that's when it goes away."

Executives joke that ten years from now people will still be discussing when PCI will finally go away.

In the meantime, PCI Express won't stand still. While products based on the first specification are more than a year away, engineers are already working on future specifications. The second-generation PCI Express will support throughput of 5 gbps; a third generation could offer up to 12 gbps.