There are multiple tape playback units attached to the Correlator. Before moving to Mark 5 disk recording, all astronomical data arrived on tape. The Correlator was designed to handle up to 24 tapes at a time; with the advent of the Mark 5 disk system, the number of playback drives has been recuded to nine.
The tape playback drives are nearly identical with the tape recorders at the VLBA sites, except that they lack a record head. This prevents accidental erasure of data. (The drives at the VLBA sites have both record and playback heads.)
Once a project has been correlated and the astronomer has had a chance to review that raw data, the tapes are released. They are degaussed (erased by a powerful magnet) and then sent back to the VLBA sites.