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LAN (Local area network) A small- to moderate-size network in which communications are usually confined to a relatively small area, such as a single building or campus.

Lands Microscopic flat areas on the surface of a compact disc that separate pits. Lands and pits are used to represent data as either a 0 or a 1.

Large Mode A format that supports hard drives that range from 504 MB to 1 GB, mapping the data to conform to the 504 MB barrier before the address information is passed to the operating system.

Latency The time between initiating a request for data and the beginning of the actual data transfer.

LBA (Logical block addressing) A method in which the operating system views the drive as one long linear list of LBAs, permitting larger drive sizes to be a accessed by the OS.

Legacy Term used to describe an application, architecture, protocol, system or system component etc. that has been in existence for a long time.

Legacy device An older device or adapter card that does not support Plug-and-Play, and may have to be manually configured through jumpers or DIP switches.

Let-through The maximum voltage allowed through a surge suppressor to the device being protected.

Level 1 cache See Internal cache.

Level 2 cache See External cache.

Limited token Applies to a FDDI network. A token sent that allows a receiving station to communicate only with the sending station, thus providing continuous communication between the two stations.

Line conditioners Devices that regulate, or condition, the power, providing continuous voltage during brownouts or spikes.

Line protocol A protocol used over phone lines to allow a connection to a network. Also called bridging protocol. The most popular line protocol is PPP (Point-to-Point Protocol).

Line-interactive UPS A variation of a standby UPS that shortens switching time by always keeping the inverter from AC to DC working, so that there is no charge-up time for the inverter.

Load size The largest amount of memory that a driver needs to initialize itself and to hold its data. It is almost always a little larger than the size of the program file.

Loading high The process of loading a driver or TSR into upper memory.

Local bus A bus connecting adapters directly to the local processor bus. On 80486 computers, it is usually a 32-bit bus running at the same clock speed as the CPU.

Logic parity A fake parity chip designed to simulate parity checking so that the user can use less expensive nonparity memory modules on a systemboard that expects parity memory.

Logical drive A drive that has been created by the disk operating system (DOS). This is done either at the preference of the user or because the DOS version does not allow a formatted capacity in excess of 32MB. A user with a 100MB hard disk will want to use more than 32MB, so a program will tell DOS there are a bunch of "logical" drives that add up to 100MB. DOS 5.0 eliminates this need.

Log on or log off The process of connecting or disconnecting your computer to another system by modem.

Lossless compression A method that substitutes special characters for repeating patterns without image degradation. A substitution table is used to restore the compressed image to its original form.

Lossy compression A method that drops unnecessary data, but with image and sound loss. JPEG allows the user to control the amount of loss, which is inversely related to the image size.

Lost allocation units See Lost clusters.

Lost clusters Also called lost allocation units. Lost file fragments that, accordings to the file allocation table, contain data that does not belong to any file. In DOS, the command CHKDSK/F can free these fragments.

Low-level format A process, usually performed at the factory, that electronically creates the hard drive cylinders and tests for bad spots on the disk surface.

Low Profile Describes drives built to the 3.5in form factor, which are only 1in high. The standard form factor drives are 1.625in high.

LSI (Large Scale Integration) Between 3,000 and 100,000 transistors on a chip. VLSI (Very Large Scale Integration) is between 100,000 and one million transistors on a chip.

LUN (Logical unit number) Also called SCSI ID. A number from 0 to 7 assigned to each SCSI device attached to a SCSI chain.