Designed as a self-study text for enlisted personnel of the Navy and Naval Reserve, this rate training manual presents information that is directly related to the professional standards for advancement to Petty Officer Third Class and Petty Officer Second Class in the Tradevman (TD) rating. (Tradevmen install, repair, modify, and maintain audio-visual aids; perform organizational and intermediate level maintenance on training devices; operate and maintain equipment used in conjunction with training devices; operate training devices and ancillary equipment to train and maintain proficiency of individuals and/or terms; assist in development, operation, and/or improvement of programs of supported activities; and construct, devise, or obtain training aids. Assignment billets include fleet submarine and fleet ballistic missile submarine trainers, radar bomb scoring units, and others.) Topical sections of the manual are as follows: administration and supply; supervision of maintenance and operations; principles of air conditioning; simulator motion systems; closed circuit TV: optics, cameras, control units, transmission; closed circuit TV: receivers, maintenance, and applications; introduction to digital simulator systems; and digital systems troubleshooting. A listing of general purpose digital computers incorporated in COG'20' training equipment is appended. The manual is indexed. The nonresident career course which follows the main manual consists of assignments and technical questions based on the occupational standards. (BL)