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LAN: See Local Area Network.

Local Area Network: A Local Area Network, or LAN, consists of a group of computers and peripherals in close proximity that have been set up so that they can communicate with one another. Macintosh computers usually connect via Ethernet or LocalTalk.

Logic Board: The logic board is the main component of any computer system. It might even be called the brain of the computer since it contains all the parts necessary to perform the many calculations that computers perform. This is where the CPU, the memory, and the main components of the computer are located.

Low-Level Format: Low-level formatting removes and then recreates the markers that organize the data on a drive. All data on the drive is usually erased. Low-level formatting is usually followed by initializing.

Mb: See Megabit

Mbps: Megabits per second.

MB: See Megabyte

MBps: Megabytes per second.

MHz: See Megahertz.

Megabit: A unit of measure for storage capacity. One megabit is equivalent to 1,048,576 bits.

Megabyte: A unit of measure for storage capacity. One megabyte is equivalent to 1,048,576 bytes.

Megahertz: A measure of frequency-one million cycles per second.

OS: OS stands for Operating System. This is the software that allows you to interact with your computer and that keeps track of files, peripherals, programs, networks, etc.

Partition: Disks contain sections called partitions. A partition is a block of addresses on a drive that the disk driver assigns to a specific volume.

Partition Map: The partition map holds information about the start, length, and type of each partition on a disk.

Parameter RAM: Also called the PRAM. This is a dedicated chip that holds information that is vital to the Macintosh computer. A battery supplies power to the PRAM so that when the Macintosh is shut down, it will retain this information. Information contained in this chip includes keyboard settings, mouse settings, and the startup device.

PCI: The standard bus on the newer Macintosh computers. It supersedes NuBus.

PRAM: See Parameter RAM.

PRAM Battery: The PRAM battery is a 3 to 4 and 1/2 volt battery that supplies the parameter RAM chip with power once the Macintosh has been turned off.

Protocol: A set of rules that dictate the operations of computers to allow them to communicate.

RAM: See Random Access Memory.

Random Access Memory: RAM is an acronym for Random Access Memory. This is memory that stores the data and programs used by your computer. Its contents are lost when the computer is turned off. RAM generally comes in packages called DIMMs and SIMMs.

Read Only Memory: ROM is dedicated chips that permanently store information. In the Macintosh the chips contain operational routines that the computer employs. ROM does not lose its information when the power is turned off. This information is permanent and cannot be changed.

Refresh Rate: This is the rate at which an image is repeated on a display surface such as a monitor.

Resolution: This is a measurement of the sharpness of an image; either by the number of pixels or the number of lines and columns on the display screen.

RGB: RGB is a video format standing for Red,, Green, and Blue, providing color images on a CRT. By combining different levels of the red, green, and blue signals almost any color can be displayed on a monitor.

ROM: See Read Only Memory.

Root Directory: The top level of a volume's directory. It may contain subdirectories (otherwise known as folders).

Sector: This is a portion of a disk drive's track and typically contains 512 bytes of data.

SIMM: See Single Inline Memory Module.

Single Inline Memory Module: A SIMM is a memory unit used by the computer. It contains RAM chips mounted on a small printed circuit board that plugs into SIMM slots, allowing for easy installation and removal.

Startup File: This file in the volume structures, if present, contains information used by the ROM to determine what program will boot the computer.

USB: USB, or Universal Serial Bus is a medium speed protocol for connecting devices to a computer. It has superseded ADB on Macintosh computers. USB is hotswappable and has a maximum transfer rate of 132 Mbps. The new USB 2.0 standard has a raw data rate at 480 Mbps. A USB port is the slot on the side of your computer (or dock) into which you plug your USB cable.

Volume: A volume refers to a logical storage unit seen by the computer as a single item. This may be a floppy disk, an entire hard drive, or one or more partitions on hard drives. Although a partition is typically seen as one volume, a RAID volume may consist of more than one partition on more than one drive.

Volume Header: This portion of the volume structures contains important data about the volume as a whole. Included is the volume name, number of files and folders, and amount of free space.

Volume Structures: A collection of data structures on a volume that is used by the file system to organize the storage of data on the volume. They include the Volume Header and Catalog.

VRAM: VRAM, or Video RAM, is the memory that holds the information that is displayed on your computer's screen.