ANALOG COMPUTERS AND DIGITAL COMPUTERS AND COMPONENTS THEREFOR, AUTOMATIC CHECKERS, [ D.C. OPERATIONAL, AMPLIFIERS, CHOPPER STABILIZED AMPLIFIERS, ] VARIABLE GAIN MODULATOR AMPLIFIERS, [ DIRECT COUPLED AMPLIFIER ASSEMBLIES, D.C. SQUARING AND SUMMING AMPLIFIERS, ELECTRIC IMPULSE COUNTER AMPLIFIERS, ] SERVO AMPLIFIERS, [ D.C. COMMUTATOR AMPLIFIERS, LINEAR DEMODULATORS, NONLINEAR DEMODULATORS, ADJUSTABLE SLOPE SAWTOOTH GENERATORS, COMPARATOR PULSE GENERATORS, LOW FREQUENCY RANDOM NOISE GENERATORS, ] ADJUSTABLE SWEEP SAWTOOTH GENERATORS, [ SQUARE WAVE ] SIGNAL GENERATORS, [ FLIP-FLOP ASSEMBLIES, LATCH ASSEMBLIES, WRITE AMPLIFIERS, READ AMPLIFIERS, AND GATES, OR GATES, POWER DRIVER ASSEMBLIES, READ HEAD SELECTOR ASSEMBLIES, CORE REGISTER ASSEMBLIES, DECODING MATRICES, ELECTRONIC SWITCH AMPLIFIERS, DIGITAL-TO-ANALOG CONVERTERS, SWITCHBLES VOLTAGE COMPARATORS, AVERAGING CARDS, DIODE MATRICES, BINARY CURRENT WEIGHTERS, PROGRAM TAPE PREPARATION UNITS ] MOTION SYSTEMS FOR TILTING THE SIMULATOR COCKPIT, APPARATUS FOR APPLYING REALISTIC LOAD FORCES TO SIMULATOR FLIGHT CONTROLS, VISUAL SYSTEMS FOR PROVIDING SIMULATED SCENES, MALFUNCTION INSERTION UNITS, RADIO AIDS SIMULATION CONTROL CONSOLES, RECORDERS FOR MAKING RECORDS OF SIMULATED PERFORMANCE, [ VIDEO FILM CONVERTERS INCLUDING FLYING SPOT SCANNERS FOR PROCESSING AND RECORDING TELEMETERED DATA ON FILM AND PLAYING BACK SUCH DATA, ] PHOTOGRAPHIC INTERPRETATION EQUIPMENT INCLUDING DEVICES FOR PRECISE MEASUREMENT AND RECORDING OF COORDINATES ON PHOTOGRAPHS, [ INTERFEROMETERS FOR PRECISE LINEAR AND ANGULAR MEASUREMENT, DEVICES FOR MARKING POINTS ON PHOTOGRAPHS, DEVICES FOR COMPARING PLURAL PHOTOGRAPHS, ] FLIGHT SIMULATORS, LAND MASS RADAR SIMULATORS AND MISSILE SIMULATORS AND PARTS THEREOF