The DFES boards sit idle until the system issues a L1accept. Then
they jump back and pull the selected event from the buffer memory and
find clusters in the CPS Stereo fibers. This list of clusters is sent
to a L2 processor farm.
The DFES boards also sent a copy of their inputs to the L3 readout crate.
DFES core design by Qichun Xu and the rest of the stuff was written
by Jamieson Olsen.
Qichun has documented the core design algorithms in his DZERO note 4162.