

I was very confused for a minute but then I realized you are talking about trackballs over mice. OP was asking about ball mice vs optical mice. Way back mice used rotary encoders to move the cursor horizontally and vertically. Those encoders were moved by a ball that stuck out of the bottom of the mouse to roll on the desk. The ball and rotary encoders were eventually replaced by the optical system we use now.










You got some pants on?