Exabyte helical scan devices at Fermilab

The Exabyte 8-mm helical-scan storage devices in use at Fermilab in a number of applications are described. These devices have the functionality of magnetic tape but use media that are much more economical and much more dense than conventional 9-track tape. The discussion covers: uses for helical scan tape systems; the initial evaluation of Exabytes; their use in the Fermilab lattice supercomputer project; their use in a VME-based data acquisition system; the problems observed in a VME environment; their use as general-purpose tape drives for VAX/VMS; a copy facility for converting 9-track tapes to 8-mm cartridges and replicating 8-mm tapes for distribution to dispersed experiment collaborators; problems observed under VMS; and diagnostics implemented to reproduce and understand the problems remaining with these devices