I had a Toshiba PoqetPad Plus back in the early 90s. It wasn't the first of it's kind either, the original PoqetPad came out in 89, well before Apple had anything close to a pad/tablet. Toshiba also had a line of tablets that ran Dos, and either Win3.0 to 3.11 (with the tiny "micro drives" that were 1" square, all of 20M..)

I still have a Point 510 running at my house. It's got Win95 on it with pen extensions. The drive bit it a long while back, so it's now got a solid-state drive instead. Makes a nice picture frame and interface console for the automation system in the house.