The on-line computational and control system for the 4π-detector CHIMERA

A commercial two-DSP-based board is the basic unit of the on-line computational and control system under development for the multidetector CHIMERA. The system design includes a small scale parallel and distributed architecture of PCs, used as both host and user and network interface, and of DSP boards, up to three for each host. The system is able to accomplish the on-beam control of CHIMERA, by means of the on-line computation of special algorithms, instead of using the usual techniques of special pulses to be sent off-beam. The physical data, collected and organized in UDP-packets by the data acquisition system, are read through a 10 Mbit/s Ethernet network. The PC-software, running under Windows NT 4.0, is based on threads and assures the communication and program managing and the result presentation. The DSP-software written in C++ takes care of the communication with the PC and of the computation. The preliminary on beam results for the first three wheels (about 100 telescopes), obtained employing two bi-processor boards located in the PCI-bus of a Pentium MMX PC are also presented