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L2CAP

Logical Link Controller and Adaptation Protocol as defined by the Bluetooth standard.

LAN

See local area network (LAN).

language monitor

A type of print monitor that provides a full-duplex communications path between the print spooler and bidirectional printers. It can also add printer control information to the data stream.

latched interrupt

An interrupt that occurs at the transition from deasserted to asserted on the IRQ line.

Also called an edge-triggered interrupt.

layered driver

One of a collection of drivers that respond to the same IRPs.

See class driver and intermediate driver.

For more information, see the topic Device nodes and device stacks.

LBN

See logical block number (LBN).

See also MCB and VBN.

legacy driver

A Microsoft Windows driver that does not support WDM. Legacy drivers usually do not support Plug and Play or power management. When possible, these drivers should be upgraded.

level-sensitive interrupt

An interrupt that occurs when the signal is asserted on the IRQ line.

linear frame buffer

Dedicated memory on a video adapter, that can hold the contents of a single screen image. A linear frame buffer is one in which the memory is linearly addressable, or "flat." This is in contrast to banked frame buffers, in which memory is partitioned into segments, or "banks."

little-endian

A computer architecture in which the byte layout in memory is as follows:

  • Byte N is the least significant byte of:
    • A word composed of bytes N and (N + 1).
    • A doubleword composed of bytes N, (N + 1), (N + 2), and (N + 3).
    • A K-byte memory entity composed of bytes N, (N + 1),...,(N + K − 1).
  • The address of a word, doubleword, or K-byte entity is the address of its least significant byte, N.

Intel microprocessors always support little-endian addressing. Some RISC microprocessors can be configured for either big-endian or little-endian addressing. For a little-endian configuration, the least significant bit of a 16-bit value is the "rightmost" bit at byte N, while the most significant bit is the "leftmost" bit of byte (N + 1).

See also big-endian.

local area network (LAN)

A group of computers and other devices dispersed over a relatively limited area and connected by a communications link that enables any device to interact with any other device on the network.

Compare with wide area network (WAN).

local bus

Usually refers to a system bus that is directly connected to the microprocessor on a system board. Used colloquially to refer to system board buses located closer to the microprocessor than are ordinary expansion buses (that is, with less buffering). This proximity to the microprocessor means that system board buses are capable of greater throughput.

local security authority (LSA)

An integral subsystem responsible for managing security access tokens for users.

logical block number (LBN)

A logical block number identifies a physical block on a disk, using a logical address rather than physical disk values (for cylinder, track, and sector). For a disk with N blocks (in other words, "sectors"), the corresponding LBNs are numbered 0 through (N – 1).

logical memory

A HAL-provided mapping between system physical memory and a device-accessible address range.

See also map.

logical unit

From a SCSI-II HBA driver's point of view, a physical or virtual peripheral device, addressable through a TID, attached to a SCSI bus.

lookaside list

A system-managed queue from which entries of a fixed size can be allocated and into which entries can be deallocated dynamically. Callers of the Ex(ecutive) Support lookaside list routines can use a lookaside list to manage any dynamically sized set of fixed-size buffers or structures with caller-determined contents.

For example, the I/O manager uses a lookaside for fast allocation and deallocation of IRPs and MDLs. As another example, some of the system-supplied SCSI class drivers use lookaside lists to allocate and release memory for SRBs.

lossy compression

The original data is not completely recoverable. Although image quality may suffer, many experts believe that up to 95 percent of the data in a typical image may be discarded without a noticeable loss in apparent resolution.

LPC

Local procedure call.

See also interprocess communication (IPC) and port object.

LSA

See local security authority (LSA).

LU

See logical unit.

See also TID.

LUID

Locally unique identifier.

See SID.

luminance

Describes the black-and-white component of a video signal. The amount of luminance contained in a video signal is directly related to the amount of light intensity. Also, brightness; one of the three image characteristics coded in composite television (represented by the letter Y).

See YUV.

 

 

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