Released in February 2005, Palm's quad-band Treo 650 is a hybrid PDA/mobile-phone device that addresses many of the shortcomings of its hugely popular predecessor, the Treo 600.

Among other improvements, the Palm OS-based Treo 650 boasts a sharp, 320 x 320 colour screen that is easy to read in sunlight (unlike the 600's screen, with its resolution of 160 x 160). In addition, the 650 features a removable, rechargeable lithium-ion battery (the 600's battery, while long-lived for a PDA/phone hybrid, could not be swapped over).

The camera module has also been updated, although it still only supports 0.3 megapixel shots. Whereas the 600's camera was basically useless for indoor photography, had no zoom, and couldn't capture video; the 650 works better indoors, has a 2x digital zoom, and can capture brief video clips. The 650 also has a built-in MP3 player that can play tunes stored on a card in the 650's SD (Secure Digital) slot. As it ships with only 22MB of internal storage memory, an extra memory card is a must.

The Treo 650 includes Bluetooth wireless capability, so you can use it with a Bluetooth headset, for example. It also supports infrared connectivity, but not Wi-Fi. It runs the Palm OS 5.4 operating system and uses Intel's PXA270 312MHz XScale processor, a much more powerful processor than that of the 600.

Hoping to spur corporate adoption of its top-of-the-line PDA/phone hybrid, Palm outfitted the Treo 650's VersaMail client with Microsoft Exchange ActiveSync capability. This allows you to sync the device with Microsoft's corporate calendar and email. The Treo 650 also supports POP3 and IMAP email.

The 650 looks very much like the 600, with its mid-size (4.4" x 2.3" x 0.9") chocolate-bar form factor and compact keyboard. Its QWERTY keyboard has larger, flatter keys that should make typing easier. The most visible difference is a slight change in the way control keys are laid out. Both a stylus and a very easy to use backlit keyboard are provided for input, but unlike other smartphones, the Treo doesn't support handwriting recognition with the stylus.

One small but differentiating feature of the Treo 650 is the small sliding button on the top of the device, which puts the phone in Silent Mode.

The Palm Treo 650 is well equipped with a high-resolution display, an improved keyboard and camera and a smooth running OS, but the lack of handwriting recognition and Wi-Fi support will disappoint some users