Abstract: A hardware cursor is implemented on a typical video display controller, and uses an unused portion of video RAM as cursor memory to store the cursor information. Since the cursor memory may be located at any unused location of video RAM, it is a virtual hardware cursor since the location of cursor data may changed as required. The operation of the cursor may be programmed, monitored and controlled via control registers. The hardware cursor monitors the video control signals to determine when to put out cursor data rather than directly outputting pixel data. The hardware cursor fetches the appropriate cursor data from the cursor memory in the video RAM during the horizontal nondisplay period just prior to a line of display data that should contain cursor data. The hardware cursor then monitors the pixel stream and outputs unchanged pixel data until a cursor location is reached, at which time the hardware cursor outputs a logical combination of cursor data, cursor color, and pixel value.

Abstract: An electro-optical displacement sensor comprises an optical source including a plurality of optical grating lines for producing from an incident optical signal a transmitted optical signal having a spatially periodic intensity pattern. Optical sensing means receives the transmitted signal as an input across a plurality of optical receptors, each of which receptors provides an output signal corresponding to the amplitude of the transmitted signal as sensed by the receptor. The receptors are spaced one from the other by a distance different from the fundamental spatial wavelength of the transmitted signal. Signal conditioning means derive a signal vector from the receptor output signals, the signal vector than being processed to derive first and second independent component signals. The component signals are then combined to produce an interpolated phase signal corresponding to the interpolated position of the grating lines relative to the optical receptors.