Abstract: In a cursor tracking system (FIG. 11), a pointing device includes a plurality of force sensors (304), optionally integrated with a keyswitch on a computer keyboard. The force sensors detect lateral and vertical forces applied to the keycap (300) by a user (302) for cursor control. Raw force data is acquired by A/D apparatus (306) and transmitted (310,312) to a host processor. Driver level software in the host linearizes the raw force values (316, FIG. 12D) to compensate for anomolies and nonlinearities in the force sensors, keyboard mechanics, and A/D. The resulting linear force values are adjusted (320) to compensate for preloading bias forces (318) on the sensors. The unbiased, linear force values and sensor configuration (322) are used to determine a net XY vector (324, FIG. 16). A speed value is determined by a quadratic mapping of the XY vector magnitude (328), taking mouse button status into account.

Abstract: Methods and apparatus are disclosed for normalizing electronic sensor data to correct for variations in individual sensor transfer characteristics which are not known in advance. A general characteristic transfer function for a sensor type of interest is determined empirically. A baseline response reading is acquired from an individual sensor, and that baseline response applied to the general transfer function to determine a specific transfer function for the individual sensor. The specific transfer function is used to calculate normalized data. One application of the invention is in computer cursor control pointing devices such as a joystick. Because the invention compensates for wide variations in sensor characteristics, inexpensive sensors such as force-sensitive resistors may be used in a joystick without sacrificing pointing accuracy and ergonomic efficiency.

Abstract: Data acquisition in a multi-function keyboard system includes both acquiring typing data by conventional keyboard scanning techniques and, simultaneously, acquiring pointing data by sampling force sensors coupled to the multi-function pointing key. The keyboard system periodically samples the force sensors to determine bias values defining a null point, and updates the bias values by a moving average calculation to compensate for manufacturing tolerance and long term drift. In response to a start pointing command from the host processor, the keyboard system transmits bias values and then pointing values, the latter being responsive to forces applied to the pointing key by the user for cursor control. The sensor values are encoded so as to pass through to the host processor in a manner transparent to application software. The system scans the force sensors periodically to acquire successive pointing values, and transmits them to the host, as long as pointing mode persists.

Abstract: A line adapter system for handling byte-oriented data transfers between remote data terminals and I/O subsystem. Working in conjunction with a controlling microprocessor, the line adapter provides input output means for regulating the baud rate of transmission to/from a remote terminal and for the timing and protocols required for both synchronous and asynchronous data transmission. The microprocessor may address and control various of the timing elements and byte to bit transfer means of the input/output circuit means. Likewise, each of the elements of the input/output circuit means may request service from the microprocessor for further detailed instructions.

Abstract: A line adapter unit working in conjunction with a microprocessor which serves to handle data transmission using the bit oriented protocol mode. The microprocessor can select any one of a plurality of input-output circuit units which provide specific control of communications to/from remote data terminals or data sets. The microprocessor can select and control various components of the input-output circuit means such as regulating the timing means and setting up command structures for controlling the type, the direction, and the conversion of serial bit data. Likewise, each component of an input-output circuit unit may request service via an interrupt to the microprocessor and receive a command or response required for further operations. Each input-output circuit unit is provided with a dedicated memory area associated with a given data communications line.