This article is from the storage FAQ part1, by Rodney D. Van Meter with numerous contributions by others.
Multiple vendors. Initially for home audio market. Original product held 1.3 GB on one 60 meter tape at about 180 KB/second. Search speeds run about 200 times nominal speed. DDS (Digital Data Storage) format has overtaken the DATA/DAT format. Two-reel cassette. http://www.dmo.hp.com/tape/_cpb0002.htm gives HP DDS drive information http://www.dmo.hp.com/tape/c1533a.htm gives specs for the DDS2 C1533A