dictionary of multimedia and internet applications: a guide for developers and users. francis botto

Print ISBN 0-471-98624-0 Online ISBN 0-470-84178-8

LAN (Local Area Network) A number of computers connected together so that users may share directories, applications, services and resources such as printers and modems. LANs are commonly used to connect all computers in a department, while Wide Area Networks (WANs) may be used to connect multiple sites. LAN data transfer rates have approximate speeds between 10 and 1000 Mbps. There are a number of internationally agreed standards by which computers forming a LAN are connected. Network topologies include the:

● star, where computers are connected using a centralised hub ● ring, where computers are connected in a chain; this is the chosen

method for small networks that are perhaps peer-to-peer configurations, which might be based on Windows 98/NT.

LAN standards include Ethernet, Token Ring and occasionally Fibre Channel (FC). The latter may be used to implement FC arbitrated loops.

(See 10base*, Active Web Architecture, Client/server, Ethernet, Inactive Web Architecture, Master/slave processing and Server.)

LAN segment A section of a LAN which is detached from the remaining network.

Lanier, Jaron A VR specialist/evangelist recognised as having invented

the term virtual reality. He founded VPL, one of the earliest VR companies.

(See VR.)

Laptop computer A portable computer compact enough to be operated from a person’s lap. Modern (about A4 size) versions are more often called notebook computers, or simply notebooks. Smaller than notebooks are the sub-notebooks, and smaller than these are palmtops manufactured by companies like Psion.

(See Display and Notebook.)

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Large-Scale Integration

Large-Scale Integration (LSI) (See LSI.)

Laser (Light Amplification by Stimulated Emission of Radiation) A light

source able to emit a coherent beam of light which is of a fixed wavelength. The device is said to ‘lase’ when producing such a ray of light.

(See LED and Optical fibre.)

Laser printer A printer which operates using toner deposits. Most are

monochrome, though there are a few colour variants (1998). Generally, they are low-cost and provide high-speed operation, and are therefore an ideal network printer solution.

Laser Vision A standard videodisc player and disc format developed by

Philips. Manufactured by Philips and other manufacturers (e.g. Pioneer), and now commonly used in IV applications as well as multimedia, it is largely a consumer product.

(See CD-ROM and DVD.)

Launch 1. The process of starting a program or application. Synonyms: Load, Open and Run. 2. A range of angles at which a ray of light must be injected into an optical fibre so that it may propagate along the cable’s entire length. The angles are within the fibre’s acceptance cone, whose size is a function of the fibre’s NA or numerical aperture. The higher the NA, the greater the light-gathering ability of the fibre.

(See Optical fibre.)

Layer An array of functions which are defined as part of a network or

communications protocol and specification. They partition functions into logical parts.

L band A section of the electromagnetic spectrum which ranges from 1.53 to 1.66 GHz and is used in satellite and microwave communications.

LCD (Liquid Crystal Display) A form of display measuring a few

millimetres in depth. Available in monochrome and colour, LCDs are used in a wide variety of appliances, including pocket televisions, notebook com-puters, PDAs, cellular phones, calculators and portable CD-ROM readers/ electronic books. Modern notebooks tend to use TFT and DSTN display technology. The former provides improved image definition.

(See LED and Notebook.)

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