LAN- A computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance via telephone lines and radio waves. A system of LANs connected in this way is called a wide area network (WAN).
Most LANs connect workstations and personal computers. Each node (individual computer ) in a LAN has its own CPU with which it executes programs, but it is also able to access data and devices anywhere on the LAN. This means that many users can share expensive devices, such as laser printers, as well as data. Users can also use the LAN to communicate with each other, by sending e-mail or engaging in chat sessions.
There are many different types of LANs Ethernets being the most common for PCs. Most Apple Macintosh networks are based on Apple's AppleTalk network system, which is built into Macintosh computers.
LCD- Abbreviation of liquid crystal display, a type of display used in digital watches and many portable computers. LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal, therefore, is like a shutter, either allowing light to pass through or blocking the light.
Monochrome LCD images usually appear as blue or dark gray images on top of a grayish-white background. Color LCD displays use two basic techniques for producing color: Passive matrix is the less expensive of the two technologies. The other technology, called thin film transistor (TFT) or active-matrix, produces color images that are as sharp as traditional CRT displays, but the technology is expensive. Recent passive-matrix displays using new CSTN and DSTN technologies produce sharp colors rivaling active-matrix displays.
LED:
Abbreviation of light emitting diode, an electronic device that lights up when electricity is passed through it. LEDs are usually red. They are good for displaying images because they can be relatively small, and they do not burn out. However, they require more power than LCDs.
Linux- A version of UNIX that runs on a variety of hardware platforms including x86 PCs, Alpha, PowerPC and IBM's product line. Linux is open source software, which is freely available; however, the full distribution of Linux along with technical support and training are available for a fee from vendors such as Red Hat Software and Caldera. Due to its stability, Linux has gained popularity with Internet Service Providers as the Operating System of choice for hosting Web servers.
Live Script- 2This is the former name of Java Script. There are few updates between the two.
Login- To attach to a computer. It has also come to represent your User ID command.
Login Script - This is the small text file that is run by the server gateway to make the attachment between it and your computer.
Loopback- A diagnostic test that returns the transmitted signal back to the sending device after it has passed through a network or across a particular link. The returned signal can then be compared to the transmitted one. The discrepancy between the two help to trace the fault. When trying to locate a faulty piece of equipment, loopbacks will be repeated, eliminating satisfactory machines until the problem is found.
LVD- Low Voltage Differential. A differential logic scheme using lower voltage levels than HVD.
MAC layer- Media Access Control sub layer in the network stack.
Mainframe- Mostly a mainframe is only a mainframe when compared to a desktop computer. It's bigger and much more powerful. Sometimes it's called a server or CPU.
MBR- Short for Master Boot Record, a small program that is executed when a computer boots up. Typically, the MBR resides on the first sector of the hard disk. The program begins the boot process by looking up the partition table to determine which partition to use for booting. It then transfers program control to the boot sector of that partition, which continues the boot process. In DOS and Windows systems, you can create the MBR with the FDISK /MBR command.
An MBR virus is a common type of virus that replaces the MBR with its own code. Since the MBR executes every time a computer is started, this type of virus is extremely dangerous. MBR viruses normally enter a system through a floppy disk that is installed in the floppy drive when the computer is started up. Even if the floppy disk is not bootable, it can infect the MBR.
MCNS- Multimedia Cable Network System Partners Ltd. The consortium behind the DOCSIS standard for cable modems.
Media
- . Objects on which data can be stored. These include hard disks, floppy disks, CD-ROMs, and tapes.
- In computer networks, media refers to the cables linking workstations together. There are many different types of transmission media, the most popular being twisted-pair wire (normal electrical wire), coaxial cable (the type of cable used for cable television), and fiber optic cable (cables made out of glass).
- The form and technology used to communicate information. Multimedia presentations, for example, combine sound, pictures, and videos, all of which are different types of media.
Megabyte: (MB) - About a million bytes of space. Actually it's 2 raised to the 20th power or 1,048,576 bytes of space.
Memory- Internal storage areas in the computer. The term memory identifies data storage that comes in the form of chips, and the word storage is used for memory that exists on tapes or disks. Moreover, the term memory is usually used as a shorthand for physical memory, which refers to the actual chips capable of holding data. Some computers also use virtual memory, which expands physical memory onto a hard disk.
Every computer comes with a certain amount of physical memory, usually referred to as main memory or RAM. You can think of main memory as an array of boxes, each of which can hold a single byte of information. A computer that has 1 megabyte of memory, therefore, can hold about 1 million bytes (or characters) of information.
Microcomputer- A category of computer that is generally used for personal computing, for small business computing, and as a workstation attached to large computers or to other small computers on a network.
Microprocessor- A silicon chip that contains a CPU. In the world of personal computers, the terms microprocessor and CPU are used interchangeably. At the heart of all personal computers and most workstations sits a microprocessor. Microprocessors also control the logic of almost all digital devices, from clock radios to fuel-injection systems for automobiles.
Three basic characteristics differentiate microprocessors:
- Instruction set: The set of instructions that the microprocessor can execute.
- Bandwidth: The number of bits processed in a single instruction.
- Clock Speed: Given in megahertz (MHz), the clock speed determines how many instructions per second the processor can execute.
- In both cases, the higher the value, the more powerful the CPU. For example, a 32-bit microprocessor that runs at 50MHz is more powerful than a 16-bit microprocessor that runs at 25MHz.
In addition to bandwidth and clock speed, microprocessors are classified as being either RISC (reduced instruction set computer) or CISC (complex instruction set computer).
MIDI- Stands for Music Instrument Digital Interface. It allows a computer to store and replay a musical instrument's output.
Minislot- (Multi-Media Extensions) A set of 57 multimedia instructions built into Intel's newest microprocessors and other x86-compatible microprocessors. MMX-enabled microprocessors can handle many common multimedia operations, such as digital signal processing (DSP), that are normally handled by a separate sound or video card. However, only software especially written to call MMX instructions -- so-called MMX-enabled software -- can take advantage of the MMX instruction set. The first generation of computers with MMX chips hit the market in January, 1997.
Modem- This is a word created out of the beginning letters of two other words: MOdulation and DEModulation. The words mean the changing of data from digital (computer language) to analog (phone line language) and then back again. It represents the purpose of your computer's modem.
Mosaic- The first Web browser to have a consistent interface for the Macintosh, Windows, and Unix environments. It was created at the National Center for Supercomputing Applications (NCSA). The success of this browser is really responsible for the expansion of the Web.
Motherboard- The main circuit board of a microcomputer. The motherboard contains the connectors for attaching additional boards. Typically, the motherboard contains the CPU, BIOS, memory, mass storage interfaces, serial and parallel ports, expansion slots, and all the controllers required to control standard peripheral devices, such as the display screen, keyboard, and disk drive. Collectively, all these chips that reside on the motherboard are known as the motherboard's chipset.
On most PCs, it is possible to add memory chips directly to the motherboard. You may also be able to upgrade to a faster CP by replacing the CPU chip. To add additional core features, you may need to replace the motherboard entirely.
MPEG- Stands for Motion Picture Experts Group. A format to make, view, and transfer both digital audio and digital video files.
MSO- Multiple Service Operator. A cable TV service provider that also provides other services such as data and/or voice telephony.
Multiplexer- This is a piece of hardware that allows one item to take the place of several. An example would be using a multiplexer to allow 10 computers to attach where only one could before.
NACS- AStands for Netware Asynchronous Communication Services.
Nanosecond- A billionth of a second. Many computer operations, such as the speed of memory chips, are measured in nanoseconds. Nanosecond is often abbreviated as ns.
Netbeui- Netbeui is short for NetBios Enhanced User Interface. It is an enhanced version of the NetBIOS protocol used by network operating systems such as LAN Manager, LAN Server, Windows for Workgroups, Windows 95 and Windows NT.
Netbeui was originally designed by IBM for their Lan Manager server and later extended by Microsoft and Novell.
Network- This a system that sends and receives data.
Network Card- Also, Network Interface Card or NIC. This is a component of a computer that enables the computer to communicate with other computers via a direct network connection.
Network Adapter- This is a hardware unit that connects a device to a communication line. For wide area networks (WAN), these adapters connect routers to the specific type of connection (T1, BRI) that is installed. For local area networks (LAN), these adapters connect workstations to the LAN (Ethernet or TokenRing) cabling.
NLX- New Low Profile Extended (motherboard form factor). The NLX form factor features a number of improvements over the previous design LPX form factor and began heavy usage in late 1997. The popularity of the design was confirmed by massive design use in 1998. The popularity has made it Intel's flagship line and one of the profit leaders in chipsets. Its features include:
- Support for larger memory modules and DIMMs.
- Support for the newest microprocessors, including the Pentium II using SEC packaging.
- Support for AGP video cards.
- Better access to motherboard components.
- Support for dockable designs in which the motherboard can be removed without tools.
Node- In networks, a processing location. A node can be a computer or some other device, such as a printer. Every node has a unique network address, sometimes called a Data Link Control(DLC) address or Media Access Control(MAC) address.
Noise- Interference (static) that destroys the integrity of signals on a line. Noise can come from a variety of sources, including radio waves, nearby electrical wires, lightning, and bad connections. One of the major advantages of fiber optic cables over metal cables is that they are much less susceptible to noise.
NTFS- Short for NT File System, one of the file system for the Windows NT operating system (Windows NT also supports the FAT file system). NTFS has features to improve reliability, such as transaction logs to help recover from disk failures. To control access to files, you can set permissions for directories and/or individual files. NTFS files are not accessible from other operating such as DOS.
For large applications, NTFS supports spanning volumes, which means files and directories can be spread out across several physical disks.
NTLDR- Short for NT Loader, a program loaded from the hard drive boot sector that displays the Microsoft Windows NT startup menu and helps Windows NT load.
NVRAM- (Non-Volatile Random Access Memory) Any type of memory that is made non-volatile by connecting it to a constant power source, such as a battery. Therefore, non-volatile memory does not lose its contents when the main power is turned off.
Object- Something that contains both the data and the application that operates on that data..
OEM- (Original Equipment Manufacturer) This is a designation for companies that manufacture equipment that is then marketed and sold off to other companies under their own names.
OOP- Stands for Object Oriented Program. A larger program made up of smaller objects.
Opacity- The quality that defines how much light passes through an object's pixels. If an object is 100 percent opaque, no light passes through it.
Operating System- The most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.
For large systems, the operating system has even greater responsibilities and powers. It is like a traffic cop -- it makes sure that different programs and users running at the same time do not interfere with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system.
Operating systems provide a software platform on top of which other programs, called application programs, can run. The application programs must be written to run on top of a particular operating system. Your choice of operating system, therefore, determines to a great extent the applications you can run. For PCs, the most popular operating systems are DOS, OS/2, and Windows, but others are available, such as Linux.
As a user, you normally interact with the operating system through a set of commands. For example, the DOS operating system contains commands such as COPY and RENAME for copying files and changing the names of files, respectively. The commands are accepted and executed by a part of the operating system called the command processor or command line interpreter. Graphical user interfaces allow you to enter commands by pointing and clicking at objects that appear on the screen.
Overclock- To run a microprocessor faster than the speed for which it has been tested and approved. Overclocking is a popular technique for eking out a little more performance from a system. In many cases, you can force your CPU to run faster than it was intended simply by setting a jumper on the motherboard. Overclocking does come with some risks, however, such as over-heating, so you should become familiar with all the pros and cons before you attempt it.
Overclocking is sometimes called speed margining
Source: "The Free On-line Dictionary of Computing, http://www.foldoc.org/, Editor Denis Howe"
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Network Technologies