Manual for the crystallographic program system used to control the 4-circle neutron diffractometer D1/TASII at DR3, Risø. The mechanical part of the diffractometer consists of a monochromator part which allows an easy change of incident neutron wavelength and a four-circle HUBER goniostate consisting of an Euler cradle (HUBER 512) and two horizontal goniometers (HUBER 440 and HUBER 430). The goniostate is computer controlled by a PDP-11/34 interfaced via CAMAC modules. The PDD-11/34 computer has a 128 k byte memory, two hard magnetic disc stations, a fast DEC-writer terminal and a screen terminal. The diffractometer can be operated remotely via modem and telephone line connections from remote stations such as the University of Århus and ILL, Grenoble. Minor parts of the software used to control the diffractometer were developed at Risø while the major parts were a generous gift to Risø from College 5, the diffraction group, at the Institute Laue-Langevin, Grenoble, France.