Abstract: A keyboard/display assembly is provided in which the individual key legends are controlled by an external computer. The computer is programmed to respond to any specific key activation in a manner defined by the current displayed legend for that key. These responses may include changing the legend on the initiating key, or those on any other keys. By this means, a small number of keys may replace an arbitrarily large number of fixed function keys.

Abstract: A tilt detector is provided especially for use in operating sub-sea drilling equipment including a tool stack at the ocean floor. One such detector is carried by the stack to produce a first output; another detector is carried by a riser pipe near a ball joint interconnecting the stack and pipe to produce a second output, and the outputs are processed to facilitate maneuvering of a drilling vesssel. The detector includes:A. a container,B. liquid in the container having an upper surface tending to remain generally horizontal as the container tilts, andC. sensors having independently movable members engaging the liquid at spaced locations to sense the relative levels of the liquid surface at said locations and relative to the container during said tilting.