Wednesday, February 07, 2007

Express breaks out of the box

PCI Express, the biggest juggernaut in interconnect technology these days, is officially available as a cabled option for a host of server, consumer and embedded uses. Infiniband, Ethernet and USB proponents don't need to worry—yet.

The new spec is aimed at enabling I/O expansion drawers for servers. OK, that is an Infiniband application. It will also link comms and other embedded systems, where I suppose Ethernet could be used. Other possible uses include a link to external graphics accelerators for those power gamers and a cabled link between notebooks and docking stations. I'm not sure what value either of those last two bring, but they do sound suspiciously like higher bandwidth alternatives to USB for consumer systems.

PCI SIG execs went deliberately slow on this spec to make sure people didn't get confused about the main purpose of Express as a chip-to-chip link. They also didn't want to raise the specter of overlap with links like Infiniband, Ethernet and USB. But now that it's out there people will likely try to push and pull it in all sorts of directions looking for new market niches in typical PC industry fashion.

For today, its just a novelty, running at the 2.5 Gbit/s rates of Express 1.0 at widths of 1, 4, 8 and 16x. Later, we'll see 5 Gbit/s versions and with initiatives like Geneseo launched last fall, who knows all what else. Watch this Express train because it's carrying a lot of freight these days.

1 comment:

Anonymous said...

The delivery of a PCI Express cable specification fulfills needs communicated to the PCI-SIG for many years now. For many people, the specification is late. Not because the PCI-SIG deemed a slow course but because some people didn't want to see it come to market or perhaps come to market in its current form. Companies like TI demonstrated proof of concept solutions years ago yet have been sidelined waiting for the PCI-SIG to get its act together and not cave into the minority who didn't like the direction being taken.

Usage models noted in the anemic press releases and news coverage talk about mobile docking or high-end game offerings. Rather myopic view of the world. Modular product construction has always been about separating product modules into practically sized and provisioned units. Simple concepts like an I/O expansion bay for servers is perhaps a no-brainer. Others such as a modular PC go beyond the uATX form factor for the desk top and address the challenges with providing multimedia PC solutions for the home or office. Who wants to listen to excessive fan noise when all one needs is the DVR component of a PC. Who wants to be bound to what PC OEM chooses to package in their boxes when they can mix-n-match components to build their own "alien" platform suited to their needs. Who wants to have to look at an ugly PC in their living room when they can put it away out of site but still have high-speed graphics next to their plasma / LCD screens.

As a replacement for USB, that seems a bit far fetched. USB works because it does not require anything more than a USB class driver to communicate with any USB device. PCI Express does not even approach anything like USB in this regard as a unique device driver must be loaded for each device and that is the anti-thesis of real plug-and-play offerings. It is true that PCI Express provides significantly more bandwidth than USB that really just points to the need for the USB group to get off their butts and provide a USB 3.0 with significantly more bandwidth (USB has known connector limitations but without increased bandwidth, it is fair for you to state that something needs to be done or its time may come to an end).

It is good to see the PCI-SIG finally deliver on a promise even if many years after the fact. Perhaps now the industry can start moving in directions that will provide opportunities to break out of this bland, homogenous environment and do something really innovative. There must be some within the PCI-SIG who can see more to PCI technology than chip-to-chip or perhaps too many see PCI and I/O like Ethernet integrated into processors in the coming years and they don't want to see the ability to differentiate get too entrenched else how will they sell their latest wiz bang idea.