Seagate STT20000N, Product Manual

Page: 63 / 70

Theory of operations Chapter 7
STT20000N Product Manual Page 55
The drive has an electro-optical sensor assembly comprised of a solid-state light
source (LED) and a photo-sensor (photo-transistor) that sense the beginning-of-tape
(BOT), end-of-tape (EOT), load point, and early warning holes of the cartridge.
Media (Travan minicartridges)
The drive is designed to use Travan TR-5 (or NS) cartridges, quarter-inch
minicartridges, and QIC-Wide minicartridges. These small (approximately 2 inches x
3 inches x 0.4 inch) cartridges house 1650-Oersted Gamma Ferric Oxide magnetic
tape. Figure 7-2 shows a Travan minicartridge.
Figure 7-2
Travan Minicartridge
The cartridge also provides write protection so that existing data on the cartridge is
not overwritten. A write-protected cartridge allows the existing data to be read but
does not allow new data to be written to the tape. The position of the sliding write-
protect tab on the cartridge determines whether or not data can be written to the
tape. See Chapter 4 for illustrations of the write-protect position.