Palm has announced the Palm m500 series of handheld devices, which run Palm OS 4.0.

The two models feature 33MHz internal processors and contain 4MB flash memory and 8MB internal RAM. Security and password-protection has been significantly improved, according to Palm. One major feature of the new range is the 16-bit colour LCD screen of the m505, which weighs 128 grams. The m500 offers a monochrome screen and weighs 99 grams.

For the first time Palm has adopted a new expansion and connectivity standard. The units feature two expansion slots, Secure Digital (SD) and MultiMediaCard expansion with a USB HotSync cradle for connectivity

Small expansion Byron Connell, Palm's vice president of product management and planning, said: "We selected SD and MultiMediaCard technology for our expansion slot because its small size allows us to maintain the elegant, sleek form factor valued by our customers. Users can now easily carry additional memory, video clips, images, applications, games, backup capability and more."

Palm's new dual-expansion architecture will be implemented across Palm's entire product range in the future. The company promises digital cameras, video recorders, Bluetooth modules, modems and GPS positioning systems for the m500 series.

Connectivity Both units can connect wirelessly to the Internet using a GSM mobile phone via infrared communication, a cable or Palm-compatible modem. They ship with Palm's Mobile Connectivity software to provide access to email, and support any POP3 or IMAP4 account.

The m500 costs $399, the m505 $449 – both should be available in May, but no UK price is available yet. The units come in silver – or Arctic Mist as Palm calls it. They ship with eBook reader software, personal calculators, DataViz Documents to Go 3.0 and more.

The company has also launched five PalmPak content cards built to use the SD interface. The packs include three travel guides, a collection of ten games and a card containing a dictionary and thesaurus.