  To collect data for the study of charm particle decays, we built a high speed
data acquisition system for use with the E791 magnetic spectrometer at
Fermilab. The DA system read out 24000 channels in 50 uS. Events were accepted
at the rate of 9000 per second. Eight large FIFOs were used to buffer event
segments, which were then compressed and formatted by 54 processors housed in 6
VME crates. Data was written continuously to 42 Exabyte tape drives at the rate
of 9.6 Mb/s. During the 1991 fixed target run at Fermilab, 20 billion physics
events were recorded on 24000 8 mm tapes; this 50 Tb (Terabyte) data set is now
being analyzed.
