Seagate STT20000A Product Manual page 83

Glossary Appendix A
A
Glossary
ATA Packet Interface—The interface providing for communications between the host computer and the drive
(standard QIC-157).
Azimuth—The angular deviation, in minutes of arc, of the mean flux transition line from the line normal to the tape
reference edge.
Backup—Copy of a file or collection of files on fixed disk, diskette, or tape. Ensures against data loss.
Beginning of Media (BOM)—Equal to the physical beginning of the tape.
Beginning of Tape (BOT)—Equal to the logical beginning of the tape.
Bezel—Front panel of a drive.
Bit—A single digit in the binary numbering system.
Bit Error Rate—The number of errors divided by the total number of bits written or read.
Block—A group of 512 consecutive data bytes plus additional control bytes recorded as a unit.
BOP—Beginning of Partition. The position at the beginning of the permissible recording region of a partition.
BOT marker—The beginning of tape (BOT) marker is a set of two holes punched side by side in the tape.
Byte—A group of 8 binary bits operated on as a unit.
Cancelmark—A "negative" Filemark or Setmark. When a Cancelmark follows as the first block in the next frame after a
Filemark or Setmark, the drive when reading the tape will logically ignore the Cancelmark and the Filemark or Setmark
it cancels.
Cartridge—An enclosure containing magnetic tape wound on two coplanar hubs.
Control field—A group of 8 bytes recorded before the data area in each block, containing information about clock
address, track address, and block type.
Cyclic Redundancy Check (CRC)—A group of 2 bytes recorded at the end of each block of data for the purpose of
error detection.
Data block—A block containing user valid data in its data field
Data Compression—The process of removing redundant data from a data stream before recording the data to tape.
Compressed data requires less storage space than uncompressed data.
Data Density—The number of single-byte characters stored per unit length of track. Usually expressed as bits-per-inch
(bpi).
Decompression—The process of restoring compressed data to its original state.
Dew—Collection of moisture in a tape drive.
STT20000A Product Manual Page 75