Development of a data acquisition system for the BABAR CP violation experiment

Experiences developing a data acquisition system for the BABAR CP violation experiment located at the Stanford Linear Accelerator Center are presented. The BABAR detector consists of multiple independent subdetectors joined with a data acquisition system consisting of a large number of embedded PowerPC single board computers residing in VME crates. The data acquisition software is layered on the VxWorks real-time operating system. It is partitionable to allow subsystems (as well as test stands) to operate independently. Data is assimilated into events through a combination of shared memory and a high performance network. This system presents data to a UNIX farm via a high speed non-blocking ethernet switch at a rate of 2 KHz. Topics such as bootstrapping and loading 200 processors, NFS file access for these processors and software development and deployment are discussed.