Logitech's timeline published on its silver anniversary declares that in 1982, "Logitech introduced its first mouse, the P-4. The P-4 used opto-mechanical technology, featuring optical encoders connected to the rollers to deliver greater tracking precision while providing the tactile response of a rolling ball," proclaiming the first 400 dpi resolution. As usual, every mouse has a tale much more interesting than the bare facts.
Logitech's co-founder, Swiss born Daniel Borel, encountered Douglas Englebart's 1960s invention of the computer mouse at Stanford University in 1976. In 1977 André Guignard and Professor Jean-Daniel Nicoud at the Ecole polytechnique federale de Lausanne in Switzerland designed the computer mouse produced by the watchmaking company Dubois Depraz SA. The opto-mechanical encoders improved on Doug Engelbart's invention but the mouse was ahead of the software development to use it. Logitech purchased and marketed it as the P4 from about 1982-1984, initially for $295.
14 Oct 2009 - World Radio Switzerland reported the passing of René Sommer, who added the micro-processor to the design of the Logitech mouse in 1985.