A microprocessor-based real-time BASIC laboratory: A pulse motor-controlled visual stimulator

Using the Commodore PET as a random pulse generator, an inexpensive visual stimulator for psychophysical experiments can easily be made at low cost. The PIA interface that connects the external experimental devices is easily accessed by PEEKing and POKEing its registers with BASIC. Using pulse motors, two independent stimulator wheels, having 24 different color filters and a 2.4 log (.1 log unit steps) unit range light attenuator, are controlled by a randomized string of pulses via a PIA port, and the responses of the observer as well as the stimulus parameters are automatically written onto the cassette memory for further data analysis.