“A datapad was a small, usually low-cost, electronic device used for storing information. Taking the place of the more primitive book, a datapad could store textual, graphic, and holographic data. They were commonly used as notebooks, day planners, calculators, and sketchpads. Some models could interface with and download information from larger computer networks. Most datapads came standard equipped with a touch-sensitive color screen, audio pickups, headphone ports, and power packs.”
There does not seem to be any sort of text messaging within the lore. E-mails exist, and must be accessed through public terminals.