Multiprocessor data acquisition system for high event rates at the Heidelberg/Darmstadt crystal ball

The Heidelberg/Darmstadt crystal ball detector uses a distributed data acquisition system consisting of a FASTBUS/CAMAC front-end, the Heidelberg Polyp multiprocessor system with thirty processor modules, and an online VAX. For this heterogeneous multicomputer system a distributed real-time operating system, which allows for even rates up to 2×10⁴ events/s, was developed. It is managed user-transparently and fault-tolerantly. An overview of the system is given. The operating system is discussed, covering its general organization, event management, and control and communication. The data acquisition software is described