The VMEbus processor hardware and software infrastructure in ATLAS

Most of the off-detector custom electronics of the ATLAS data acquisition system such as the Read-Out Drivers or the Trigger and Timing Control system have been implemented in VMEbus. The paper describes the process of selecting a common VMEbus processor module for all VMEbus systems in ATLAS and the problems encountered during the evaluation of different candidate modules. It describes the motivation for developing a VMEbus low level software package and presents the special features of this package. Finally some performance figures for VMEbus transfers are presented.