If you are looking at a computer screen, your right hand is probably resting on a mouse. To the left of that mouse (or above, if you’re on a laptop) is your keyboard. As you work on the computer, your right hand moves back and forth from keyboard to mouse. You can’t do everything you need to do on a computer without constantly moving between input devices.
There is another way.
A device called a “keyset” could help us navigate virtual environments without moving your hands back and forth. With the mouse in your right hand, the keyset would occupy your left hand. Its five buttons resembled piano keys.
Doug Engelbart invented the keyset in the 1960s. Engelbart was also the person who invented the mouse.