Palm's CEO has written a letter to its developer community assuring them the company is not planning to dump its Palm operating system.

The letter from Ed Colligan comes amid unrest from Palm OS developers following the company's new Treo smart phone that will run Windows Mobile instead of its own OS.

The letter pledges Palm's commitment to developing Palm OS-based PDAs and smart phones even after the launch of the Windows Treo early next year. Palm pioneered the handheld computing market but the move away from Palm OS with the new Treo has been filling message boards and discussion forums with concerns over its long-term support.

"This is not a zero-sum game! This market is in its infancy, and if we can expand out opportunities by being a strong cross-platform provider of world-class smartphone products, then we should do so," Colligan wrote.

With PDA shipments in a free-fall, companies such as Palm are pouring resources into smart phones such as the Treo 600 and 650, both of which run Palm OS. Both Treo devices have been popular with consumers, but Palm thinks it can have greater success among business customers by releasing a Treo that uses Microsoft's mobile operating system. The thinking is that IT managers will prefer to use a Microsoft-based mobile device that can be integrated with other Microsoft products they already use, such as the Exchange e-mail server.

"It's a fact that a large majority of businesses around the world use a Microsoft-based infrastructure across their IT assets. And many of those companies simply aren't open to products that use another OS. We can either answer that marketplace demand with a Windows-based product, or we can walk away from that business," Colligan wrote.

Access recently bought PalmSource, the former Palm division that was responsible for developing new versions of the Palm OS. Access intends to continue with PalmSource's plans to implement a Linux micro-kernel into Palm OS, but many developers have been uneasy about the future prospects for the OS given Palm's embrace of Microsoft, and Sony's retreat from the PDA market.

That unease has been fueled by the flop of Cobalt, a version of Palm OS tailored for smart phones. Palm refused to use that version in its Treo products, instead turning to an older version developed for PDAs called Garnet and writing the code for the phone capabilities itself. To date, no smart phones based on Cobalt have been released, while Windows Mobile's market share continues to grow.

"We have sold more than 30 million Palm OS-based products over the years, and it is not our intent to walk away from such a strong and loyal user base," Colligan said.