By Dirk Abeln* and Juergen Kopf;
Institut fuer Anorganische und Angewandte Chemie der Universitaet Hamburg, Martin-Luther-King-Pl. 6, D-20146 Hamburg, Germany.
One of the first scientific instruments to be controlled by a computer was the single crystal diffractometer (Busing, W. R. and Levy, H. A., Acta Cryst., 1967, 22, 457). Early computer-contolled diffractometers were built at Hilger & Watts (Y290), Enraf-Nonius (CAD4), Philips (PW1000) and Siemens (AED). The programs developed for those instruments were written in assembler, mostly for a DEC PDP-8 computer. The first diffractometer software, completely written in the high-level computer-language FORTRAN IV, was the control program for the Syntex P21.

The past ten years have seen a revolution in computing and graphics hardware with the arrival of PCs and powerful graphic workstations which become increasingly faster and cheaper. New desktop systems, like GEM, WINDOWS or X/WINDOWS, allow an unexperienced user easy interaction with the computer.

In connection with the electronic rebuilding of a 22 years old, mechanically still reliable Hilger & Watts (Y290) we have developed a new graphically oriented program for the diffractometer control which uses the above mentioned advantages. A new interface (Lange, J. and Burzlaff, H., J. Appl. Cryst., 1991, 24, 190), using a 68008-based single-board microcomputer for serving the four stepper motors of the four circles, is connected to an ATARI Mega ST2 via the serial interface RS232. The diffractometer control software is completely written in FORTRAN77 and has the following features:

The power of this new program Y290 is derived from a sophisticated menu-driven user interface which is much easier to use than the ``classical'' command-line input.
Last changed: 16-Nov-2001. Jürgen Kopf