Abstract: A microprocessor-based keyboard/display is described in which the function of the keys can be varied automatically depending on the instrument to which the keyboard/display is connected. The keyboard/display comprises a microprocessor, a read only memory in which is stored an operating program for the microprocessor, a keyboard having a plurality of keys, a display, and means for connecting said microprocessor to another instrument. In accordance with the invention, the program stored in said read only memory is responsive to a signal from the instrument to which said keyboard/display is connected whereby upon receipt of a signal from one type of instrument at said keyboard/display at least some of said keys of said keyboard are given first functions and upon receipt of a signal from a second type of instrument said keys are given different functions.

Abstract: A microprocessor based single loop control instrument is described which can operate as any one of several different types of controllers, each of which can provide two or more different modes of operation. The control instrument comprises a microprocessor, a read only memory in which is stored the operating program for the control instrument, means for causing the control instrument to operate as one of the types of controllers provided for by a program stored in the read only memory and means for selecting the mode of operation of the controller. Further, in accordance with the invention, the control instrument is supplied with a control panel controlled by a second microprocessor and connected to the first microprocessor by a communication bus. The second microprocessor controls a bar graph display for displaying at least one signal related to the operation of the control instrument as well as means for selecting the signal that is displayed.

Abstract: A method and apparatus are disclosed for calculating gas flow through an orifice using the complete American Gas Association gas flow equation, for selecting specific values to be used in said calculation in accordance with the specific orifice used, and for selectively displaying operating and test parameters.