Though not identical in principle, personal digital assistants, handheld PCs, and programmable calculators serve many the same functions as the old pocket computers, generally with significantly more computing power in a package the same size or smaller. The main distinction is that more modern designs (with the exception of programmable calculators) usually do not have included programming capability and are usually set up to act as clients of a larger system rather than as self-contained environments of their own, whereas the early pocket computers had their own data storage and input/output facilities such as printers and tape drives.
