BUNCH Number, ROTATION Number. DØ identifies the part of the beam responsible for a collision by two numbers, the BUNCH and ROTATION number. Roughly speaking, the rotation number identifies how many revolutions the beginning of the beam has made (leading bunch), and the bunch number identifies the bunch within a given rotation.

CCLUT. Coordinate Conversion Look Up Table (on TFC). This table converts silicon information from the hardware address (Seq ID, HDI, chip, strip) to the corresponding DØ global coordinates used in the track fitting.

CFT. Central Fiber Tracker. The large volume portion of the DØ tracking system. It has 8 layers (each having sublayers) of scintillating fibers. Each layer provides position and direction information for one or more track segments.

CTT (or L1CTT). Central Track Trigger. The level one trigger component formed using CFT information

DPM. Dual Port Memory. Computer memory which can be simultaneously read and/or written by two different data sources.

DSP. Digital Signal Processor A special purpose CPU which is optimized for certain linear algebra operations, typically vector dot products (like those used in fast fourier transforms).

DWORD. In the PCI standard, a 32-bit wide memory location

FIFO. First-In, First Out memory. This memory is arranged as a queue. The data can be read out only in the order it is written in.

FPGA. Field Programmable Gate Array. A class of computer chips which perform logic operations and/or processing. The chip is programmed for specific tasks, and the program is specified in terms of logic operations (and, or, not) and basic elements(counters, registers, adders,...). Typcially, the program can be modified only by resetting the chip.

FRC. Fiber Road Card. One (of three) elements of the STT. This board is responsible for receiving the CTT data and for all overall coordination and synchronization of the STT with the outside world.

Hotlink. A serial transmission (hardware) protocol.

LUT. Look Up Table. A memory which is used to perform tabulate the results of a calculation. The memory address is formed from the input to the calculation, and the memory contents are the result of the calculation. All possible calculations must be performed in advance, with the results forming the (static) look up table.

LVDS.Low Voltage Differential Serial protocol. A high-speed serial data transmission hardware standard.

MLUT.Matrix LUT (on TFC). A look up table which holds the matrices needed in the linear algebra which determines the track trajectory.

Seq ID, HDI,CHIP. The basis information from the silicon tracker (SMT) is a list of which individual strips recorded the passage of a particle. A given strip is identified by the triplet (Seq ID, HDI, Chip), and a fourth number, the SVX channel.

SMT. Silicon Microstrip Tracker. The high-precision innermost element of the DØ tracking system. This is comprised of barrel and disk assemblies of silicon wafers (and mechanical support).

STT. Silicon Track Trigger. The level two trigger element which uses SMT and CTT data to increase the precision of the track reconstruction.

STC. Silicon Trigger Card. One (of three) elements of the STT. This board is resonsible for receiving the raw SMT data, determining where particles went through the detector(called clustering), and associating the clusters with tracks CTT tracks.

SVX. ???. This chip is an 128-input analog to digital converter with multiplexed read out. It is used to read out (among other subsystems) the SVX information.

SCL. Serial Command Link. This is a bus from the overall DØ trigger control computer to each element of the trigger system. It provides synchronization and control information. Among this information are the bunch and rotation numbers, and trigger qualifiers used to indicate processing options.