Abstract: An earth boring tool control system for monitoring the spatial orientation of a remote boring tool (10) and adjusting the path thereof to maintain a predetermined course (22), is comprised of a vertical position detector (26) for determining the elevation of the tool relative to a desired course, including a sensor head member (32) in operative engagement with the tool for establishing a pressure head of fluid characteristic of the vertical disposition of the tool, a pressure sensor member (50) for sensing a differential pressure in response to variations in the height of the pressure head, and a fluid circuit (40, 44) communicating between the sensor head member and the pressure sensor member for transmitting any pressure variations to the sensor member; a horizontal position detector (28) for determining the azimuth of the tool relative to the course, including Hall generators (80, 82) in operative engagement with the tool for developing normalized output signals (90, 92) proportional to deviations in an am