Logitech Trackman Portable Mouse Trackball
This laptop clip-on trackball came out around year 1991.
![logitech trackman portable mouse](itb/logitech_trackman_portable_mouse_85170.jpg)
The bar shaped thing is the left button, the dot shape is right button.
You clip this onto the side of your portable laptop.
Laptop exists in 1991. It isn't like today's. It was thick and heavy, with a tiny screen, about 640x480 pixels.
![logitech trackman portable mouse trackball 24354](itb/logitech_trackman_portable_mouse_trackball_24354.jpg)
See also:
![logitech trackman portable mouse 74537](itb/logitech_trackman_portable_mouse_74537.jpg)