Unsafe at any key size
Published on Jan 1, 2000
A teaching machine system for displaying selected frames from a multiple-frame film strip wherein instructional material is contained on a first portion of each frame and code indicia including an excursion instruction is contained on a second portion of each frame. The code indicia associated with a frame being displayed render selected answer keys operative whereby a student selects an answer, and establish an initial counting state in a counter, which is counted down as the frames of the film strip pass a projection gate in proceeding to the next frame to be viewed. When the counter reaches a predetermined minimum counting state, dependent on the particular answer key selected by the student, the film strip is stopped and the next frame is viewed. An alternate mode of operation is provided wherein fixed excursions of a predetermined number of frames occur for each answer key. A dynamic reading method is employed for reading code indicia on the film strip to reduce the number of photodetectors required. A performance memory is provided for branching to advanced material after a predetermined number of correct answers, and a no-go circuit is provided for discouraging frivolous or improper depression of answer keys. The film transport includes a self-threading feature, and operates at two speeds to reduce excursion time and to provide a smooth controlled stop sequence. A novel cassette-type supply reel provides automatic mode selection, and novel reel hub assemblies provide for bidirectional film movement with a single bidirectional drive motor.