The unrest among Palm OS developers over Palm's forthcoming Windows Mobile-based Treo smart phone has prompted Palm President and Chief Executive Officer Ed Colligan to pen a letter to Palm's developer community with promises to continue releasing Palm OS products.

The letter, a copy of which was sent to IDG News Service, pledges Palm's commitment to developing Palm OS-based personal digital assistants and smart phones even after the launch of the Windows Treo early next year. It will be posted on the home page of Palm's members-only PluggedIn community for software and hardware developers later on Tuesday or early on Wednesday, a Palm spokeswoman said.

Palm, which pioneered the handheld computing market, announced it would use Microsoft's Windows Mobile on a version of its combination PDA-mobile phone Treo products in September. The announcement was troubling for some long-time Palm OS developers, who have been filling message boards and discussion forums with comments suggesting that Palm's long-term support for the Palm OS is waning, according to Colligan's letter.

"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 Co. 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, long-time licensee Sony Corp.'s retreat from the PDA market, and the age of the Palm OS.

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.

Palm executives said repeatedly at the company's September press conference with Microsoft that it planned to release future Treo smart phones and PDAs with Palm OS. Colligan noted Tuesday that earlier this year Palm extended its Palm OS license until 2010.

"We have a rich product roadmap of Palm OS-based handheld computers, mobile managers and Treo smartphones that we intend to deliver," Colligan wrote. "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."