THOR-a commodity component prototype for the ATLAS Event Filter

The ATLAS Event Filter prototype developed at the University of Alberta (the THOR project) is being used in the context of the DAQ-1 project to study issues related to the implementation of the sub-farm model using commodity components and open source software. The prototype consists of seven dual Pentium II 450 MHz machines connected via a fast Ethernet switch and will soon be upgraded to nine dual Pentium 450 MHz machines connected in a 3/spl times/3 array using Scalable Coherent Interconnect (SCI). The entire prototype is placed behind a firewall machine which serves as the control centre for the processor farm.