No abstract

The paper describes a program system, written in Fortran, designed to control an automatic four-circle diffractometer for neutrons, either with or without an analyser. A simplified version can be used to control a powder diffractometer. This system, initially developed on the Tel6m6canique T2000 computer for three diffractometers at the Institut LaueLangevin at Grenoble, has been rewritten for the Digital Equipment Corporation (DEC) PDPI1 computer in such a way as to make the best possible use of the supervisor and the facilities available on this system.