Page 62 - Electrical Engineering Dictionary

fully associative cache memory and in some (2) in contrast with a symmetric multipro-
translation look-aside buffers or page transla- cessor, asymmetric multiprocessor is a mul-
tion tables of the hardware to support virtual tiprocessor in which the processors are not
memory. Given the user-space address of a assigned equal tasks. The controller (mas-
page it returns the physical address of that ter) processor(s) are assigning tasks to (slave)
page in main memory. Also called content processors and controlling I/O for them.
addressable memory (CAM).
asymmetric multivibrator a multivibra-
associative processor a parallel proces- tor where the output voltage represents a train
sor consisting of a number of processing el- of narrow pulses. Most asymmetric multivi-
ements, memory modules, and input–output brators use a slow charge of a large timing ca-
devices under a single control unit. The ca- pacitor by a small current (or via a large resis-
pability of the processing elements is usually tor) and a fast discharge of this capacitor via
limited to the bit-serial operations. a switch. The charge process determines the
duration of space; the mark duration, which
associativity In a cache, the number of coincides with the time allowed for discharge
lines in a set. An n-way set associative cache of the timing capacitor, is usually determined
has n lines in each set. (Note: the term by a small time constant of the circuit con-
“block” is also used for “line.”) trolling the switch. Asymmetric multivibra-
tors find applications in voltage-to-frequency
converters. Also called multivibrators with a
astable multivibrator the circuit that is
small mark/space ratio.
obtainedfromaclosed-loopregenerativesys-
tem that includes two similar amplifiers of
asymmetric resonator standing-wave
high gain connected with each other via cou-
resonator in which either the reflectivities or
pling circuits with reactance elements. More
the curvatures of the primary mirrors are un-
frequently are used RC-coupling circuits
equal.
(free-running RC-multivibrators, emitter-
coupled multivibrators), yet RL-circuits,
asymmetrical silicon controlled rectifier
usually as transformer coils, may be used as
(ASCR) (1) an inverter grade SCR fab-
well (magnetic multivibrators).
ricated to have limited reverse voltage capa-
bility. Fabrication with asymmetrical volt-
astigmatism a defect associated with op-
age blocking capability in the forward and
tical and electrostatic lenses where the mag-
reverse direction permits reduction of turn-
nification is not the same in two orthogonal
on time, turn-off time, and conduction drop.
planes; common where beam propagation is
(2) a thyristor that has limited conduc-
not along the axis of rotation of the system.
tion in the reverse direction to gain increased
switching speed and low forward voltage
asymmetric digital subscriber line (ADSL)
drop. See also silicon controlled rectifier
a digital subscriber line (DSL) in which the
(SCR).
rate from central switching office (CO) to
customer premise is much faster than the rate
asymptotic 2-D observer a system de-
from customer premise to CO.
scribed by the equations
asymmetric multiprocessor (1) a ma-
z i+1,j+1 = F 1 z i+1,j + F 2 z i,j+1
chine with multiple processors, in which the
+ G 1 u i+1,j + G 2 u i,j+1
time to access a specific memory address is
different depending on which processor per- + H 1 y i+1,j + H 2 y i,j+1
forms the request. ˆ x i,j = Lz i,j + Ky i,j
c
2000 by CRC Press LLC