A great historical overview of Apple’s efforts at tablet computing, starting from some early work in 1979.
“The Apple Graphics Tablet was the beginning of tablet computers at Apple. It’s a crude example of a modern Wacom Tablet. As illustrated in a 1981 Apple Spring Catalogue, “The Apple Graphics Tablet turns your Apple II system into an artist’s canvas. The tablet offers an exciting medium with easy-to-use “tools” and techniques for creating and displaying pictorial information”. It was developed by Summagraphics, and uses magnetostriction. The built-in alloy wires localize a stylus on the x, y, and z axis points. Software entitled, “Utopia Graphics System”, developed by musician Tod Rundgren, was the paint program that it worked with.”