The KiddiComp concept, envisioned by Alan Kay in 1968 while a PhD candidate,and later developed and described as the Dynabook in his 1972 proposal "A personal computer for children of all ages", outlines the requirements for a conceptual portable educational device that would offer similar functionality to that now supplied via a laptop computer or (in some of its other incarnations) a tablet or slate computerwith the exception of the requirement for any Dynabook device offering near eternal battery life. Adults could also use a Dynabook, but the target audience was children.
Part of the motivation and funding for the Dynabook project came from the need for portable military maintenance, repair, and operations documentation. Eliminating the need to move large amounts of difficult-to-access paper in a dynamic military theatre provided significant US Department of Defense funding.
Though the hardware required to create a Dynabook is here today, Alan Kay still thinks the Dynabook hasn't been invented yet, because key software and educational curricula are missing.