VMD provides optional support for Spaceball six-degree-of-freedom input devices. The Spaceball may be used to rotate, translate, and scale molecules, using up to 6 control axes simultaneously (3 axes in translation, 3 in rotation). The Spaceball can be used both independently and simultaneously with the mouse. With the spaceball in one hand and the mouse in the other, a user can perform complex picking and identification operations more efficiently, since the mouse can be left in pick mode (for example) while the Spaceball is used to perform rotations, translations, and scaling operations with the other hand.