Viper 60s Theory Of Operation And Maintenance Manual page 168

GLOSSARY
BEGINNING-OF-TAPE.
Tape position: the beginning of the tape.
BLOCK.
Unit of data transfer used by the tape backup system; consists of 1024 bytes.
BOT.
See Beginning-of-Tape.
BUFFER.
An area of the memory used for temporary storage and manipulation of data.
BYTE.
Eights bits of binary data acted upon as a unit.
CRC.
Cyclical redundancy check.
CDB.
See Command Descriptor Block.
CLUSTER.
An integral number of disk sectors grouped together for the purpose of allocating
space on a disk.
COMMAND DESCRIPTOR BLOCK.
A group of bytes used to communicate commands between the
host and the tape drive.
CONNECT.
The action of an initiator when asserting control over the SCSI bus to select a target
for an operation.
CONTENTION.
Condition when two or more devices contend for the use of a processor or try to
access the system bus at the same time.
DEFAULT.
A preset value used by a program if no other value is specified.
DISCONNECT.
The action of a target releasing control of the SCSI bus.
DMA.
Direct Memory Access; direct transfer of data to or from RAM, bypassing the CPU and
increasing speed of computing process.
END-OF-DATA.
Tape position: the end of recorded data.
END-OF-TAPE.
The end of the tape.
EOT.
See end-of-tape.
HEXADECIMAL NOTATION.
The base sixteen numbering system. Viper hexadecimal values are
shown as 02h
HOST.
The computer that issues commands to the tape drive over the SCSI bus.
INITIATOR.
A SCSI device that requests an operation by another SCSI device (the target).
Viewed from tape drive perspective, the Initiator is usually the host computer.
LSB.
Least significant byte or least significant bit.
LOGICAL UNIT NUMBER (LUN).
A three-bit device identifier for a logical unit. The Viper 150 is
always addressed designated LUNa.
G-1