Abstract: A display device includes improved raster scan apparatus which provides for the video display of information in timed synchronization with cycles of AC power. The raster scan apparatus includes a circuit which monitors the periodicity of the AC input power to the display device. This circuit is operative to initialize certain raster scan logic which thereafter authorizes the next raster scan sweep. In this manner, each raster scan is synchronized with respect to the cyclical AC power. This synchronization eliminates visible distortion on the video output of the display device.

Abstract: Apparatus for processing bits of information magnetically recorded on a credit card or similar article. The apparatus includes a slot for receiving the credit card as well as a transducer for reading the bits of information when the card is manually moved thereunder. Circuitry connected to the transducer is operative to read the recorded bits of information. Sensors, provided at each side of the transducer, detect and time the initial movement of the card. An alarm circuit is operative to generate a warning if the card does not proceed at the minimum speed necessary to read the bits of information.