Abstract: A system for controlling the pressure in a chamber with a computer controlled exhaust throttle valve. A characterization relationship describes the static properties of the valve geometry, valve actuation mechanism and gas flow properties. This characterization relationship can comprise a theoretical or empirical function which associates a sufficient number of valve positions with the corresponding pressure, and may be parameterized by other auxiliary variables such as inlet gas flow values, gas types and compositions. An inverse relationship between the current measurable variables of the process, such as pressure, inlet flows and other auxiliary parameters is defined. A linearization method uses the inverse relationship to modify the effect of the valve positioning on the corresponding value of pressure in such a way that the combined behavior of the process and the linearization method yields a linear relationship between a new control variable and the pressure.

Abstract: Telephone station equipment consisting of a phone device interconnected with a personal computer. The phone device includes a conventional telephone handset and a keypad employing pushbutton display keys each of which has a writable keyface display for visually indicating the function of the key or other information to the user. The personal computer is connected to both the phone device and to one or more telephone communications channels and is programmed to display prompting information on the key displays and respond to keypress events to perform the functions indicated. The user can perform a variety of telephone system management tasks solely by viewing and manipulating the phone device keypad, including manual dialing, redialing, speed-dialing from a directory of commonly called numbers, making flash disconnections, forwaring calls, controlling call waiting and caller I.D.