Twisted-pair variant of 100BASE-X. Uses the physical characteristics of FDDI's TP-PMD, but uses Ethernet framing and CSMA/CD. Used in SGI Origin and Onyx2 systems.


100Mbps CSMA/CD 802.3/Ethernet-like LAN also known as Fast Ethernet. There are two types: 100BASE-TX (used in SGI Origin and Onyx2 systems) and 100BASE-T4.


A type of fan used in the GIGAchannel expansion cabinet. Instead of blades that resemble the propeller of a ship, the blower uses blades that more closely resemble a paddle wheel (or water wheel). As the blower spins, it impells air out the bladed sides of the wheel, creating a slight vacuum in its center, thus drawing more air into the blower.


A measure of data equal to 8 bits. See also kilobyte, megabyte, and gigabyte.


Memory used exclusively by the CPU for temporary storage and calculations.


A specific I/O bus; typically used to describe SCSI bus numbers (for example, SCSI channel 1). See also controller.


The metal framework to which components of a computer are attached.


Literally the circuitry (typically an ASIC) that controls a bus or device. Also used to describe a SCSI bus as a synonym for “channel.” See also channel.

CrayLink Interconnect

An SGI bus technology for linking nodes. See also node.

dual in-line memory module (DIMM)

A module to which are attached SDRAM chips.


Error correction code; used in memory to correct for single-bit errors.

electromagnetic interference (EMI)

Electromagnetic radiation that is produced by electronic equipment, and that can interfere with radio and television reception and cause problems with other electronic devices. Computer equipment is designed to contain EMI to various extents as determined by regulatory agencies.


The specification for SCSI-2, on a 16-bit bus, running at 20 MHz, and capable of 40 megatransfers per second. See also Ultra SCSI.

gigabyte (GB)

A measure of data equal to 1024 megabytes (MB). See also byte, kilobyte, and megabyte.

hertz (Hz)

Frequency in cycles per second.

kilobyte (KB)

A measure of data equal to 1024 bytes. See also byte, megabyte, and gigabyte.

kilogram (kg)

A unit of weight equal to 1000 grams (about 2.2 pounds). See also pound.

loopback cable

A cable that loops signals coming out of a chassis back into the chassis, either through the same connector or different connectors. Typically, a loopback cable is used for testing or to bypass equipment outside the chassis. In the case of Origin200 GIGAchannel, an XIO cable can be used as a loopback cable between the XIO A and XIO B connectors. See also loopback mode.

loopback mode

When an Origin200 GIGAchannel server is operating with an XIO cable attached (looped) between its XIO A and XIO B connectors. In loopback mode, the Origin200 GIGAchannel server module can run without the GIGAchannel expansion cabinet attached because the XIO bus signals are looped back from the XIO A connector to the XIO B connector.

MAC address

Unique hexadecimal serial number assigned to each Ethernet network device to identify it on the network. With Ethernet devices (as with most other network types), this address is permanently set at the time of manufacturer. Each card has a unique MAC address, so that it will be able to exclusively copy packets that are meant for it off the network.

megabyte (MB)

A measure of data equal to 1024 kilobytes (KB). See also byte, kilobyte, and gigabyte.


One million bytes of combined SCSI commands and data transferred across a bus.


An Origin200 chassis, CPU, and memory.

module system controller (MSC)

The board that contains logic to control low-level system functions, such as power-on, power-off, and fan speed. Located behind the front panel, the Origin200 MSC also contains the NIC that holds the system serial number.

mounting ear

An angled sheet-metal adapter used to attach a chassis to the rails of an equipment rack.

number in a can (NIC)

A device mounted on a circuit board that contains information such as the serial number of the board and other information. In Origin200 systems, the NIC mounted on the module system controller contains the system serial number.

node (node board)

A board that contains one or two R10000 processors and their caches, a section of the global main memory, a crosstalk I/O port, and an inter-node routing network connection (CrayLink Interconnect).

peripheral component interconnect (PCI)

A bus specification.


A unit of weight equal to 16 ounces (about 0.64 kilograms). See also kilogram.

programmable read-only memory (PROM)

Memory that contains data, often configuration information and low-level programs, that usually is not updated by the system. Certain types of PROMs can be updated, for example, during software installation.


Redundant array of inexpensive disks.

random access memory (RAM)

Memory used for calculations and temporary storage. See also cache.

read-only memory (ROM)

Memory that contains data (often configuration information and low-level programs) that cannot be updated by the system.


Small computer systems interface. See also channel and controller.


A general term for all the components of a computer. In the case of an Origin200 system, this consists of one or more nodes as well as the software installed on them. See also node.

system console

A device to which IRIX prints various messages, and which is the first serial I/O device to become active when the system boots. Unlike the diagnostic port, you can log in to IRIX via the system console. In an Origin200 server, the system console is connected to serial port 1.

terminal emulation

The process by which software emulates a character-based (ASCII) terminal. See also terminal emulator.

terminal emulator

Software that emulates a character-based (ASCII) terminal. Typically used with modems for remote, dial-up access, a terminal emulator can also be used over a serial cable connected directly between two computers. Terminal emulators are often called a “modem software” or “communication software.”

Ultra SCSI

The specification for SCSI-2, on a 16-bit bus, running at 20 MHz, and capable of 40 megatransfers per second. See also Fast-20.

Uniform Resource Locator (URL)

The address by which resources (files) are identified on the World Wide Web.


An acronym for Crosstalk I/O, an SGI bus technology for linking I/O components of a system.