What is the X in X-mas?
A very small computer: Silicon Valley's future may hinge on winning the palmtop computer race
[1990s+ Computers; modeled on desktop, laptop]
(Or "pocket computer", "Hand-held Personal Computer", H/PC) A small general-purpose, programmable, battery-powered computer cabable of handling both numbers and text (in contrast to most pocket calculators) which can be operated comfortably while held in one hand. A palmtop is usually loaded with an operating system such as Windows CE. Data can be transferred between the palmtop and a desktop PC.
A palmtop is very similar to a Personal Digital Assistant though a palmptop may have a larger keyboard and more RAM and is possibly more general purpose in concept, if not in practise.
The Psion Organiser is one of the best known examples. [Was it the first?]