From The Free On-line Dictionary of Computing (8 July 2008) [foldoc]:
palmtop
Hand-held Personal Computer
H/PC
pocket computer
<computer> (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?]
(1998-04-19)