100BaseT

Based on the IEEE 802.3u standard, 100BaseT is the Fast Ethernet specification of 100Mbps baseband that uses UTP wiring. 100BaseT sends link pulses (containing more information than those used in 10BaseT) over the network when no traffic is present. See also 10BaseT, Fast Ethernet, and IEEE 802.3.

100BaseTX

Based on the IEEE 802.3u standard, 100BaseTX is the 100Mbps baseband Fast Ethernet specification that uses two pairs of UTP or STP wiring. The first pair of wires receives data; the second pair sends data. To ensure correct signal timing, a 100BaseTX segment cannot be longer than 100 meters.

100Base-X

100Base-X provides a data transmission speed of 100 Mbps using baseband. 100Base-X supports many different cable standards.

100VG-AnyLAN

Defined in the IEEE 802.12 standard for the transmitting of Ethernet and token ring packets at 100 Mbps. Uses four twisted pair cables.

10Base2

An Ethernet topology that supports 10 Mbps, uses baseband signals and can span 200 meters. Also called Thinnet.

10Base5

An Ethernet topology that supports 10 Mbps, uses baseband signals and can span 500 meters. Also called Thicknet.

10Base-FL

An Ethernet topology that supports 10 Mbps, uses baseband signals and fiber-optic cable.

10BaseT

Part of the original IEEE 802.3 standard, 10BaseT is the Ethernet specification of 10Mbps baseband that uses two pairs of twisted-pair, Category 3,4, or 5 cabling – using one pair to send data and the other to receive. 10BaseT has a distance limit of about 100 meters per segment. See also Ethernet and IEEE 802.3.

2B+D

Common abbreviation for Basic Rate ISDN, which has two B, or bearer, channels and one D, or data, channel. See also 23B+D and Basic Rate ISDN.

23B+D

Common abbreviation for Primary Rate ISDN, which has 23 B, or bearer, channels and 1 D, or data, channel. See also 2B+D and Primary Rate ISDN.

24/7

Abbreviation for round-the-clock availability, implying that the service is available 24 hours a day, 7 days a week.

3+

A network operating system, originally developed by 3Com, that implemented Xerox Network System (XNS) transport protocols and Microsoft MS-Net file sharing.

3Com Corporation

One of the largest manufacturers of network hardware in the world, particularly known for LAN and WAN products, including remote access products, hubs, network interface cards, Gigabit Ethernet, and multimedia over networks. The company’s PalmPilot handheld computer has proved to be extremely popular, with more than one million units sold to date. In 1997, 3Com merged with U.S. Robotics in a deal worth $6.6 billion. For more information on 3Com, see www.3Com.com.

3270

A general description for the family of products from IBM that includes terminals, printers, and terminal cluster controllers. These products all communicate with a mainframe computer using the SNA (Systems Network Architecture) protocol.

4B/5B Encoding

A data-translation scheme used to precede signal encoding in FDDI (Fiber Distributed Data Interface) networks. In 4B/5B, each group of four bits is represented as a five-bit symbol, which is then associated with a bit pattern, which in turn is encoded using a standard method, often NRZI (non-return to zero inverted). See also Manchester Encoding.

4.4BSD Lite

A version of the 4.4 Berkeley Software Distribution (BSD) Unix from which all the AT&T code has been removed in an attempt to avoid licensing conflicts. It is not possible to compile and then run 4.4BSD Lite without a preexisting system because several important utilities and other files from the operating system are missing. The 4.4BSD Lite version has served as the basis for several other important Unix implementations, including FreeBSD and NetBSD. See also Berkeley Software Distribution Unix, FreeBSD, NetBSD, Unix.

5B/6B Encoding

A data-translation scheme used to precede signal encoding in 100BaseVG networks. In 5B/6B, each group of five bits is represented as a six-bit symbol, which is then associated with a bit pattern, which in turn is encoded using a standard method, often NRZI (non-return to zero inverted). See also Manchester Encoding.

680×0

A family of 32-bit microprocessors from Motorola, used in Macintosh computers and many advanced workstations. The 680×0 is popular with programmers, because it uses a linear-addressing mode to access memory, rather than the segmented-addressing scheme used by Intel coprocessors. See also PowerPC.

802.2 Frame

The default frame type used on Ethernet networks by all NetWare versions 3.12 and later.

802.3 Frame

This was the default frame type used in all Novell NetWare products versions 3.11 and earlier.

80286

Also called the 286. A 16-bit microprocessor from Intel, first released in February 1982, used by IBM in the IBM PC/AT computer in 1984. Since then, it has been used in many other IBM-compatible computers. The 80286 uses a 16-bit data word and a 16-bit data bus, with 24 bits to address memory.

80386

The Intel microprocessor that introduced the power of 32-bit computing to the IBM PC-compatible computer. The 80386 also introduced memory management, which allowed the use of virtual memory and hardware level multitasking, and protected mode, which increased the stability of operating systems by allowing them to restrict the activities of user-level programs. See also i486 and Pentium.

80486

Also called the 486 or i486. A 32-bit microprocessor introduced by Intel in April 1989. The 80486 adds several notable features to the 80386, including an onboard cache, a built-in floating-point processor, and a memory management unit (MMU), as well as advanced provisions for multiprocessing and a pipelined execution scheme.

9-Track Tape

A tape storage format that uses nine parallel tracks on 1/2-inch, reel-to-reel magnetic tape. Eight tracks are used for data, and one track is used for parity information. These tapes are often used as backup systems on minicomputer and mainframe systems; digital audio tapes (DATs) are more common on networks. See also Quarter-Inch Cartridge.