Early 1991 snapshot of Forth program to control the test harness of the Electron Drift Instrument of the Center for Astrophysics and Space Sciences at UCSD, later launched on the Space Shuttle.<p>There are regular posts about Forth, including regular mentions of its use in the space program, but little on actual production code.<p>As expected, it is extremely terse and difficult to unravel, but there are numerous explanatory comments.