Research In Motion Ltd.'s chief executive gave the first peek at the BlackBerrys he is counting on to stop his company's slide, but drew a tepid response that heightened concerns about whether the company's products can compete with the iPhone.

RIM has promised to deliver the next-generation BlackBerrys sometime later this year -- a complicatedproject because they will run on a new operating system. CEO Thorsten Heins didn't show the actual phones Tuesday or even specify a date for their release, but he did give away thousands of prototypes to software developers at the company's annualconference here.

RIM is hoping to heat up developers' lukewarm embrace of the operating system that will power the new phone. Mr. Heins, however, seemed to struggle at times to rally his audience. Applause was tepid as he walked through a few features on the prototype. Other features, including predictive touch-screen typing features and a camera tool that allows users to select photos taken split-seconds apart to edit pictures, drew a heartier response.

While some analysts said the prototype looked like it held promise, many investors were disappointed with the lack of details from the company about the actual phone -- including a specificlaunch date.

RIM shares fell 5.7% Tuesday, amid a broader market rally. The stock finished down 82 cents at $13.48, leaving RIM with a market value of $7 billion.

RIM popularized mobile email but failed to keep up with the move to touchscreen phones and mobile Internet use. Now its market position is eroding. Research firm comScore said Tuesday that RIM's share of the U.S. smartphone market fell to 12.3% at the end of March, down from 16% just three months earlier.

That left it a distant third behind devices powered by Google Inc.'s Android software, at 51%, and Apple Inc.'s iPhone, at 30.7%, both of which gained ground.

The BlackBerry prototype unveiled Tuesday, which RIM executives said may or may not resemble the real phones, looked similar to products some of RIM's biggest competitors are already churning out. For instance, it sported a touch-screen-only interface, instead of the thumbs-friendly keyboard on most BlackBerrys. (RIM didn't rule out that the real phone would have a keyboard.)

RIM said the prototypes would give developers the basic tools and feel of the new device to allow them to design for the platform.

'It's about giving developers what they need to prepare for the launch of BlackBerry 10,' said Chris Smith, a RIM vice president. 'The phone is not intended to be representative of what the final BB10 products will be like, but it is a sneak peek into what the guiding properties will be.'

The new device will run off a new operating system, called BlackBerry 10, a version of which already powers RIM's PlayBook tablet. Apps developers have so far failed to rally around the new OS, a concern given that consumers now factor the broader ecosystem of games, applications and media into their decisions about which phones to buy and keep.

A recent survey by Appcelerator and research firm IDC found that only 16% of developers were 'very interested' in developing apps for BlackBerry products, compared with 89% for the iPhone and 79% for the Android operating system.

Underscoring the importance RIM puts in getting more developers behind BlackBerry 10, RIM said Tuesday it would essentiallyguarantee developers they would make at least $10,000 on any app BlackBerry licenses. It promised to pay developers the difference if they didn't make at least that amount on any apps that make an initial $1,000.

Reactions to the prototype Tuesday were mixed. Some analysts were disappointed the device didn't preview more features. But many existing RIM customers and partners -- along with some outside analysts -- said they were enthusiastic.

RIM's share price has tumbled amid falling sales, a number of product delays, the poor debut of its PlayBook tablet early last year and operational blunders.

Mr. Heins, who took over earlier this year, has committed to seeing the BlackBerry 10 launch through, though he has also said that he is considering a wide range of strategic options.