This report examines the knowledge and experience gained from the implementation of three PLATO IV terminal devices: the microfiche system, the touch panel, and the random-access audio device. These devices, when attached to a PLATO IV terminal, serve to expand the types of input and output which can be managed by the terminal. For each peripheral device, the report documents the operating characteristics and their adequacy, the efforts and skills required to use the device, and alternatives which were considered. Also included are managerial considerations and some brief comparative data. As an evaluation report designed to aid decision makers, it contains no instructions detailing how to acquire, maintain, or operate these devices. It concludes that the touch panel is generally reliable, the slide selector is adequate but good microfiche are hard to produce, and that early audio devices are barely satisfactory. It is noted that on-site testing and maintenance are needed for reliable performance and that authors wasted time and money trying to take shortcuts. (Author/SC)