A September 1981 article in Byte magazine describes the "Graphics Mouse" component of the Alto personal computer:
The mouse is a small box with three buttons on the top and several ball bearings on the bottom. A slender cable connects the mouse to the Alto keyboard (see photo 4). The buttons are named red, yellow, and blue, although the physical buttons are all black. The mouse is typically held in the user's right hand and rolled along the table on a soft piece of plastic that provides traction for the ball bearings.
Movement is detected by the motion of one of the ball bearings. The mouse reports changes in position to the Alto. From this, a cursor on the Alto display can be positioned. The physical position of the mouse on the table is unimportant, since only the change in position is reported. The mouse graphics interface is considerably more flexible and comfortable than a bit pad, joystick, or trackball. Many Alto programs can be controlled with the mouse alone independent of a keyboard.
And then there's this prescient bit at the end:
A stand-alone Alto is usable, but the best configuration is a group of Altos connected by an Ethernet system. Since the Ethernet system is a local network, a special device called a gateway was developed to allow local Ethernet networks to speak to other Ethernet networks or packet networks of other types. Many companies are researching network schemes that would allow packet transmission across cable-television lines. Since these cables are currently installed in many homes and buildings, it is not difficult to imagine a city with an "information grid," analogous to the electric-power grid that exists today. Combined with an electronic mail system (a prototype called Laurel is used on Altos today) the possibilities are staggering.
Staggering indeed. (via Muxway)