jumper
An electrically-conductive component placed over pairs of pins extending from the circuit board on the hard drive jumper block to connect them electronically. Jumper placement is one method of designating a hard drive as Master or Slave.
KB
Kilobyte. Usually, this is a unit of 1000 bytes. In computer memory, which is partitioned into sizes that are a power of 2, a kilobyte is equal to 210 or 1024 bytes.
LAN
Local area network. A system in which computer users in the same company or organization are linked to each other and often to centrally-stored collections of data in LAN servers.
landing zone
A location on the inner part of a disk to which heads move when commanded or when powered off. User data is not stored in the landing zone.
laser textured media
A treatment that minimizes friction and wear on a hard drive. The precision and consistency of this process contributes to the robustness of WD drives.
latency
The period of time that read/write heads wait for a disk to rotate to the correct position for accessing requested data. For a disk rotating at 5200 RPM, average latency is 5.8 milliseconds (one-half the revolution period).
LBA
Logical block addressing. A method of addressing sectors on a drive as a single group of logical block numbers rather than cylinder, head, and sector addressing (CHS). LBA allows accessing larger drives than is normally possible with CHS addressing.
LED
Light Emitting Diode. An electronic device that lights up when electricity is passed through it.
logical address
A storage address, which may not describe the physical location, for requesting data retrieval. A controller converts a request from a logical to a physical address and is able to retrieve data.
logical drive
A section of a hard disk that appears to be a separate drive in a directory structure. Up to 23 logical drives can be created on an extended partition of a hard disk, using letters A-Z with three reserved: A and B for diskette drives, and C for the first primary DOS partition. Logical drives are commonly used for group directories and files.
low-level formatting
A process, also called initialization, that prepares a hard drive to store data. Low-level formatting sets up the locations of sectors so that user data can be stored in them. Low-level formatting is performed at the WD factory; users need not perform low-level formatting on a WD drive.
LUL
See Ramp Load/Unload
