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APPENDIX A
GLOSSARY OF TERMS
APPENDIX
A:
GLOSSARY
access point--Beginning of a sequence of compressed records at which point codewords to a decompression
algorithm must start---whether or not the required data is at the beginning of the sequence.
Automatic Track Finding (ATF)--A method of ensuring the head is in the center of the track being read.
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, where the leader tape is jointed to
the magnetic 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.
Byte--A group of 8 binary bits operated on as a unit.
Cassette--An enclosure containing magnetic tape wound on two coplanar hubs and driven by an external
drive.
Compression Ratio---The ratio comparing the amount of uncompressed data to the amount of compressed
data. It is obtained by dividing the size of the uncompressed data by the size of the compressed data.
Crosstalk--Signals from adjacent tracks interfering with signals from another track.
Data Area---The third section of a tape on a DAT cassette, which is written as a series of groups beginning
with the special Vendor Group.
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.
A-1
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