I'm not looking to argue over the meaning of "invent" or "personal computing", but I'll point out that Alan Kay wrote a 1972 paper "A Personal Computer for Children of All Ages" that pretty much describes the modern laptop or tablet. (He even mentions ad blockers!) Xerox PARC went on to implement a lot of this in the Xerox Alto.
It's worth taking a look at the paper to see how many "modern" ideas were described in 1972: http://www.vpri.org/pdf/hc_pers_comp_for_children.pdf