Attention is focused on all potential methods of drilling safer and cheaper. Real time data from the bit offers the greatest potential for meeting these needs. As a result, numerous companies are actively competing to develop this oil field service capability and to capture a world wide market. Two basic categories of service are sought. The first, and highest priority, is drilling safety and efficiency; the second is real-time logging, or formation evaluation. This study addresses the types of systems being studied, describes company activity and projects underway, estimates the practical potential for success and considers the commercial market for successful systems. The need for research data on bit hydraulics and drill string dynamics, special deep, hot or sour gas situations and other relatively unusual requirements may become exceptions to the general conclusions that are drawn. Historical and present activity are documented through presenting the results of extensive literature and patent researches. A breakdown is presented of activity by company along with names and addresses for further contact.