The ORPHEE versatile low-cost multiprocessor system for data acquisition and control of neutron spectrometers

The new data acquisition and control system of the neutron-scattering instruments at the ORPHEE research reactor is described. The existing system has undergone a complete change: the original CAMAC system and minicomputer controlling each experiment have given way to commercial CPU boards and microcomputers like the IBM-PC. The communication links between these two components are the IEEE 488 or RS-232 standards. Emphasis is placed on the flexibility and modular nature of such a system, which makes a maximum use of commercial products, guaranteeing reliability and ease of use. A study of the requirements and evolutions, technical as well as philosophical, is detailed to demonstrate the motivation of the choice of the system architecture. A survey of the various hardware and software achievements, and finally, an overview of future improvements is given.