Clarke was a great ambassador for science and technolgy in popular culture. He's like your favourite uncle who can discuss groundbreaking ideas in a way that you'd imagine you'd talk to someone over a cup of tea. I'm sure he had a far more in depth grasp of many technolgies than he presented in many of his novels (so as not to overwhelm more casual readers than some them - probably in technology industries or academia, etc.).

Relax people. What Clarke is stating here was already then mainstream discussion topics among computer science academia. These are not his prediction nor ideas alone. Alan Kay had already envisioned portable Tablet computers 5 years prior.
Most important, Douglas Englebarts groundbreaking lecture showcasing the first real graphical user interface in 1968. He made a video conference call, showed off the keyboard and mouse combo, introduced a file system, monitor, word processor, real time editing and