The name of the game for PDAs is expansion. On Tuesday here at PC Expo, Palm added another handheld to its arsenal when Sony announced it would ship a Palm OS-powered personal digital appliance, or PDA, this fall. Handspring , meanwhile, made several small steps toward fulfilling the full potential of its Palm OS-powered Visor, announcing that 11-of-38 plug-and-play Visor modules were now shipping, with the remainder to follow closely behind. Not to be out done, the original PDAs from Palm added new expansion capabilities by integrating the Secured Digital (SD) Card expansion slot. In other words, on Day 1 of PC Expo, handhelds were hotter than the massive-but-muggy interior of the Javits Center. Spokespeople for the likes of Palm, Handspring and Sony each said they intended the grow the PDA market, rather than fight over each other's market share. Market share figures from Dataquest, meanwhile, suggest an already healthy market, with 4.9 million units being shipped in 1999 accounting for $1.6bn in revenue worldwide. Most of those sales occurred in the United States. Palm made up 67 percent of the market units shipped worldwide. "Our main focus will be brick and mortar channels where we can get at consumers who haven't been buying PDAs as much as business people. Our goal is to grow the market, not to take away from other players," said David Yang spokesperson for Sony. Differentiating the PDA devices will be important factor if the manufacturers are going to avoid stepping on each other's toes, though. Sony's focus will be on the consumer and to attract them they will use their significantly influential consumer brand. Technologies spanning other products lines such as notebooks and digital cameras may also attract consumers, including Sony's proprietary memory technology, MemoryStick, and its scroll button navigation tool, the JogDial. Many of the details of Sony's Palm OS-powered unit, such as the name of the unit or even its price, are yet to be determined. What do you think? Tell the Mailroom. And read what others have said. Take me to the Mobile Technology Special