From 2004, a new I/O technology called PCI Express will power desktops, notebooks and servers. Should you defer your hardware upgrade plans?

PCI or Peripheral Component Interconnect--a conduit between the microprocessor and external devices--is going into "retirement".

Introduced more than a decade ago, PCI is based on a parallel model operating at 33MHz and over the years, PCI has undergone several facelifts but increasingly demanding and complex I/O requirements for computing and communications applications, such as gigabit Ethernet and video on-demand, have put a strain on the system.

About two years ago, the PCI Special Interest Group (PCI-SIG) started touting a new architecture called 3GIO (third generation input-output), and this specification was later christened PCI Express.

Unlike its predecessor, PCI Express is based on a serial model and boasts transfer rates of 2.5GHz. This eliminates system chokes when dealing with applications which require higher I/O bandwidth, explained Bala Cadambi, Intel's PCI Express Initiative manager.

PCI Express-powered machines are expected to be smaller and faster due to lower pin counts. According to PCI-SIG, a typical 64-bit, 133MHz PCI device currently provides about 11.5MBs of bandwidth per signal pin. However, the PCI Express architecture provides 125MBs bandwidth per signal pin.

"The vast reduction in pin count increases design flexibility and ultimately lowers cost for manufacturers and end-users," Cadambi said at the recent Asia-Pacific Intel Developer Forum in Taipei.

The first PCI Express compliance workshop will be held in Milpitas, CA. in December followed by Taipei in the first quarter of 2004, he added.

Final call for CardBus
For many years, PC Cards have extended notebook computers' feature set--such as enabling connectivity to a LAN--with a plug and play approach. CardBus-based PC Cards, the 32-bit industry standard backed by PCMCIA (Personal Computer Memory Card International Association), an international standards body and trade association, has been the dominant platform.

Earlier this year, PCMCIA heralded a new PC expansion card called ExpressCard: which will have two serial interfaces (USB 2.0 and PCI Express) built in. One of the main differentiating factors with the ExpressCard is it's ubiquitous nature.

"What we'll initially see [next year] is both desktop and notebook designs utilising PCI Express slots and connectors," said Brad Saunders, PCMCIA's chairman.

ExpressCards come in two flavours--the smaller version is 34 millimeters wide by 75 millimeters long and 5 millimeters high. The L-shaped larger version has the same length and height but is 54 millimeters at its widest point. Existing CardBus cards measure 85.6 millimeters in length and 54 millimeters in width.

According to Saunders, the larger card's extension is designed to take advantage of applications such as Smart Media and compact flash memory.

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CardBus is equipped with 68 pins compared with 26 pins for ExpressCards--an architecture which offers approximately 50 percent in cost savings for manufacturers.

Since there's no backward compatibility or bridging technology between CardBus and ExpressCard, there was concern over having to "discard" legacy machines but Saunders said the association has communicated to users that PCI Express will solve more than scalability issues.

"Another benefit is the standard is optimised for desktops and mobile computers so you're going to ultimately see smaller footprints and cheaper production costs-- which could ultimatelty lead to more affordable machines," Saunders added.

Bob Hayward, senior vice president at Gartner Asia-Pacific, concurred with Saunders. "I don't think PCI Express will have a major impact on tech spending because when it's time to spend, IT departments will spend," Hayward said.

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