The goal of the Digital Display Working Group (DDWG) is to end the era of dueling digital monitor interfaces and get all the ducks — PC makers, graphics houses, monitor makers — lined up in the same row. According to sources, the members have agreed on the essentials of DDI and will spend the next few weeks hammering out "most, if not all" of the final details.

"We've tried to get as much done as possible, knowing it's important to get something out there because people are waiting for this," said Scott Macomber, president of Silicon Image Inc. (Cupertino, Calif.).

DDI is very much a "convergence spec," as one source put it, with something for almost everyone. "There will be a declaration of convergence at the meeting," said Alan Petersburg, worldwide brand manager for IBM Visual Products (Research Triangle Park, N.C.).

"What's key is that it won't break any existing technology," said Peter Wheeler, product marketing manager for commercial desktop products at graphics house ATI Technologies Inc. (Unionville, Ontario).

The interface is based on the PanelLink TMDS (transmission minimized differential signaling) technology of Silicon Image, Petersburg said, as are two competing interface proposals: Plug & Display, developed by VESA and backed by IBM; and Digital Flat Panel, developed by Compaq.

"DDWG [members] are the core players in the global PC business and the primary stake holders in this interface issue," said David Mentley, vice president at Stanford Resources Inc. (San Jose, Calif.). "It looks like the best way to resolve the issue."

According to Wheeler of ATI, DDI is essentially a modification of Compaq's Digital Flat Panel (DFP) scheme, "making it wider and faster and throwing in a few features." Like DFP, the new interface excludes the Universal Serial Bus, said a source at a monitor company. "You don't want a USB connector change, there are so many USB connectors around," he said.

On the other hand, according to Petersburg, DDI departs from the digital-only DFP and "acknowledges" the Plug & Display (P&D) philosophy that "in the future, we'll want a single connector that has both digital and analog connections inside of it."

Sources said DDI will resolve certain high-level issues that neither P&D nor DFP addresses, such as whether the host or the monitor is responsible for image manipulations like scaling and gamma correction.

"We spent a lot of time on things that give display independence," said Macomber. For things like scaling, "DDWG will define an architectural solution that makes sense," while also making allowance for an installed base that may implement things differently. "We tried to think through all the typical problems, the things that are obviously going to happen as we move from where we are to where we want to be," he said.

How willing are the current players to leave behind the digital monitor interfaces they've already fielded? "We don't want to throw our engineering out the window, but if something else becomes the standard, we'll adopt it," said Tom LaRocca, who until recently was manager of product marketing for monitors at Compaq Computer Corp. (Houston). "Whatever way it goes, we'll follow it." IBM will also support DDI, Petersburg said, as well as P&D and analog interfaces.

"We are designing for this as we speak," said a spokesman for Number Nine Computer Co. "In the meantime, we will offer graphics solutions that concurrently support both digital and analog standards."

Texas Instruments Inc. (Dallas), a major supplier of LVDS (low-voltage differential signaling) chips for notebook computers, reportedly is carrying on a TMDS development project. The company has not endorsed the LVDS Display Interface (LDI) for desktop monitors devised by National Semiconductor Corp. and backed by Silicon Graphics Inc. TI, the leader in mobile LVDS flat-panel interface products, "is investigating desktop flat-panel solutions including TMDS and LVDS," said Fred Zust, worldwide marketing manager for LCD interface products at TI.

For its part, SGI's Visual Systems Group (Mountain View, Calif.) is "committed to working with standards bodies like the DDWG to assure that whatever standards do emerge support displays with high resolution, performance and quality," said marketing manager Steve Proffitt.

Monitor and graphics houses are relatively unfazed by the prospect of another digital interface. "We've all had to build adapter dongles all along [to support different interfaces]," said Darwin Chang, vice president of technology at Princeton (Santa Ana, Calif.).

Said ATI's Wheeler, "Dongles in this industry are no surprise. We dongle P&D and DFP right now. That mentality can be used going forward. We can even convert an LVDS panel to TMDS with a small attachment card. It's not clean, of course, for the consumer, but it's one way of preserving the installed base."

"We have demonstrated that an ATI DFP card works perfectly fine with our P&D monitors," said Petersburg, "if you just have the right dongle in between. It will be a similar situation with the converged [DDI] connector."

One pitfall noted by the monitor source is that DDI means "a connector change." He speculated that the interface will have about 30 pins, the same as P&D. DFP has 20 pins and LDI has 36.

"DFP is easy to adapt, P&D is relatively painful," the source said. "But the guys who really lose are SGI and Number Nine. Their current-generation designs will be obsolete and they have redesigns in the works already." He believes the two will "drop LDI as soon as they can."

It's not clear how complete the DDI spec will be by the time of the Intel Developer Forum. "We may not have all the answers now, but we'll show a compelling road map," said Macomber. "We've defined something that gives us all the headroom we need to solve all problems we see coming up. Security, for example, in the long run is going to be a fundamental problem. So security is on the [DDWG] agenda."

DDI products will appear "maybe in the second half of 1999," said Chang, though Wheeler speculated it would be "Q1 2000 at the earliest."