Page 101 - Electrical Engineering Dictionary

stance, an acousto-optic modulator can be branch history table a hardware compo-
said to operate in the Bragg regime or al- nent that holds the branch addresses of pre-
ternatively in the Raman–Nath regime. See viously executed branch instructions. Used
also Raman–Nath diffraction regime. to predict the outcome of branch instructions
whentheseinstructionsarenextencountered.
braking operating condition in an electric Also more accurately called a branch target
motor in which the torque developed between buffer.
the stator and rotor coils opposes the direc-
tion of rotation of the rotor. Typical braking branch instruction an instruction is used
methods in DC machines include “plugging” to modify the instruction execution sequence
in which the polarity of either the field or of the CPU. The transfer of control to an-
the armature coil, but not both, is reversed other sequence of instructions may be uncon-
while the rotor is turning, “dynamic brak- ditional or conditional based on the result of
ing” in which generator action in the arma- a previous instruction. In the latter case, if
ture is used to dissipate rotor energy through the condition is not satisfied, the transfer of
a braking resistor, and “regenerative brak- control will be to the next instruction in se-
ing” in which generator action in the rotor quence. It is equivalent to a jump instruction,
is used to dissipate rotor energy by return- although the range of the transfer may be lim-
ing electric power to the power source as the ited in a branch instruction compared to the
rotor slows. Typical braking methods in AC jump. See also jump instruction.
machines include switching of the phase se-
quence of the supply voltage, dynamic brak- branch line coupler coupler comprised
◦
ing through the armature coils, and varying of four transmission lines, each of 90 electri-
the frequency of the AC supply voltage. See cal length, arranged in a cascaded configura-
also phase sequence. tion with the end of the last transmission line
section connected to the beginning of the first
transmission line to form a closed path. The
braking resistor resistive elements which
input, coupled, direct, and isolated ports are
can be switched into the electrical system to
located at the connection point of one trans-
create additional load in the event of a tran-
mission line with the next one.
sient disturbance, thus limiting the generator
rotor acceleration such that the system can
branch penalty the delay in a pipeline
more readily return to synchronism.
after a branch instruction when instructions
in the pipeline must be cleared from the
branch address the address of the in-
pipeline and other instructions fetched. Oc-
struction to be executed after a branch in-
curs because instructions are fetched into the
struction if the conditions of the branch are
pipeline one after the other and before the
satisfied. Also called a branch target address.
outcome of branch instructions are known.
branch circuit the three components of branch prediction a mechanism used to
an electrical circuit are source, load, and in- predict the outcome of branch instructions
terconnecting circuit conductors. A branch prior to their execution.
circuit is an electrical circuit designed to de-
liver power to the lowest-order load(s) served branch relation the relationship between
on a facility. It includes the overcurrent de- voltage and current for electrical compo-
vice, circuit conductors, and the load itself. nents. Common branch relations are Ohm’s
Law and the lumped equations for capacitors
branch current the current in a branch and inductors. More complex branch rela-
of a circuit. tionships would be transistor models.

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2000 by CRC Press LLC