Abstract: A video recorder and playback device allowing simultaneous recording and playback of program material, including means for controllably varying a time delay between the recording and playback of recorded material. This allows, for example, playback of previously recorded material to be temporarily stopped and then resumed without interrupting the recording of new material. A user can arrange to start recording a broadcast program (while the user is not at home, for example) in the conventional way via stored instructions, and then begin watching the recording several minutes or hours later, before the program is over, without stopping the recording. The user can also interrupt the playback of a program that is being recorded as it is being watched (to take a telephone call, for example), and then resume playback of the program (after the phone call is over) without stopping the recording. The user can then watch the rest of the program delayed by a time period equal to the length of time of the interruption.

Abstract: A system which samples and records the locations of opaque particles accumulating on a surface. The system represents graphically the geometrical distributions of the particles through an integral electronic hardware/software subsystem. The key component is a radiant energy sensitive sensor which produces the sampling surface. The sensor is exposed to a constant level of radiant energy. Opaque particles becoming resident upon the sensor surface inhibit sensitization of the surface by the radiant energy and thereby indicates the presence and location of the particle. Embodiments of the sensor include charge coupled devices (CCDs), photodiode arrays, intrinsic or extrinsic "bulk" material, and optically- or UV-erasable memories.