how could leave out the Pocket PC or the Apple Newton?
I'm coming down with a damn cold and getting tired. I didn't include any of the other PDAs either. But although they were predecessors to tablets, I don't consider any of them to be true Tablets. The form factors were too small.
Some people even want to include fictional ancestors as well. . . such as the Star Trek TriCorder. I didn't include those either. Others wanted to include purely reading devices. Nope. Not those either.