A system of programs and routines is presented that is expressly designed to be user friendly, as much as possible, and to give the real possibility of performing all the stages of crystallographic computation on a personal computer. The package has been developed in a modular way to support adapted versions of some popular crystallographic programs, such as MULTAN, SHELX, PLUTO, ORTEP and PARST. Original facilities are provided for file and system management and molecular graphics on screen display, plotter and matrix printer. The result is a powerful menu-assisted package, which represents the first example of an independent crystallographic work station running under the MS–DOS operating system. The package has been implemented on an IBM AT and can be used without modifications on any XT/AT-compatible personal computer.