It's so small, you can put it in your shirt pocket and forget about it, unlike a Newton. It's got a very well-written operating system, PalmOS, resulting in very snappy response. It synchronizes with desktop programs at the touch of a single button. You can pick them up at local electronics stores, like Circuit City and the like. Also, you can mail order them direct from US Robotics .
Several models are now available.
The original Pilot 1000 and 5000 can still be gotten, and are a steal when combined with the new 1 meg Pro upgrade card. The newer PalmPilot Personal and Professional have a newer version of PalmOS and include backlighting. Then go to Calvin's PilotFAQ site , which conveniently indeed has more info than I can possibly include here. That would be Edward Keyes , the programmer. He cut his teeth on the ZX-81 Sinclair, then moved up through the VIC 20, the Commodore 64, and the IBM PC before finally finding the Macintosh, the BeBox, and of course the PalmPilot.