Technical information

Glossary
Glossary-4 Tenth Edition 9871
library control unit (LCU) Resides in the
EM. The LCU receives instructions from the
LMU and decodes them into specific move
commands. The LCU sends the move
commands to the robot where they are
executed.
library management unit (LMU) The
portion of the ACS that manages from 1 to 16
LSMs and communicates with the host CPU.
library storage module (LSM) The portion
of the ACS that provides the storage area for
cartridges plus the robot that moves the
cartridges.
light emitting diode (LED) An electronic
device used mainly as an indicator on status
panels to show equipment on/off conditions.
LMU See library management unit.
local area network (LAN) A computer
network over which devices within the
network access each other for data
transmission purposes. The LMU and
attached LCUs are connected by a local area
network.
lock access door A door mounted on the
access door for safety reasons. The procedure
to open and close the LAD prevents anyone
from being in the LSM when the robot is
moving.
LSM See library storage module.
M
magnetic tape. A tape with a magnetizable
layer on which data can be stored. (T)
manual mode A library operating in manual
mode does not communicate with the client/
host and requires human assistance to
perform cartridge operations. Manual mode
occurs when the robot is unavailable to the
client/host.
microcode A code, representing the
instruction of an instruction set, that is
implemented in a part of storage that is not
program-addressable. (IBM) See also
firmware.
modem Modulator/demodulator. An
electronic device that converts computer
digital data to analog data for transmission
over a telecommunications line (telephone
line). At the receiving end, the modem
performs the inverse function.
mount To place a cartridge tape in a drive
or transport and make it accessible to the
host system.
N
Nearline An ACS component that acts as the
interface between the operating system and
the rest of the automated library.
O
offline. Neither controlled by, nor
communicating with, a computer. (IBM)
online. Pertaining to the operation of a
functional unit when under the direct control
of the computer. (T)
operating system. Software that controls
program execution.
operator control panel. A functional unit
that contains switches used to control all or
part of a computer and possibly the
indicators giving information about its
functioning. (T)
optical character recognition (OCR)
Character recognition that uses optical means
to identify graphic characters. (I) (A)
optical character recognition (OCR)
label An external label attached to a
cartridge that is both human- and
machine-readable.