Historical Document · 1989
US Patent 4,845,652: Generic Equation Solver Interface for Solving Mathematical Equations (Hewlett-Packard)
Hewlett-Packard's patent on the menu-key equation solver: priority 29 May 1986, granted 4 July 1989.
Historical Document · 1989
Hewlett-Packard's patent on the menu-key equation solver: priority 29 May 1986, granted 4 July 1989.