NonStop S-Series Server Description Manual (G06.24+)

Glossary
HP NonStop S-Series Server Description Manual—520331-003
Glossary-75
position-independent code (PIC)
the first character and a position ID as the second character. For example, the cluster
switch name X3 indicates that the cluster switch serves the external ServerNet X fabric
and occupies position 3 in the topology. Supported values for position IDs are 1
through 9 or A through Z. Currently supported topologies (star, split-star, and tri-star)
use position IDs 1, 2, and 3.
position-independent code (PIC). Executable program or library code that is designed to
be loaded and executed at any virtual memory address, without any modification.
Addresses that can be modified by the loader do not appear in PIC code, only in data
that can be modified by the loader. See also dynamic-link library (DLL).
POSIX. The Portable Operating System Interface, as defined by the Institute of Electrical
and Electronics Engineers (IEEE) and the American National Standards Institute
(ANSI). Each POSIX interface is separately defined in a numbered ANSI/IEEE
standard or draft standard. The application program interface (API), known as
POSIX.1, has become ISO/IEC IS 9945-1:1990.
power distribution panel (PDP). A group of panel assemblies that composes a single
panel that includes buses and overcurrent protection devices (with or without
switches). A PDP is used for the control of power circuits.
power distribution unit (PDU). See computer-room power center (CRPC).
power domain. A set of customer-replaceable units (CRUs) and field-replaceable units
(FRUs) that share a set of power rails. For Telco Central Office (CO) systems, the
power domain is the entire system.
power factor. The ratio of real power to apparent power (that is, kilowatts/kilovoltamperes).
The power factor for a sinusoidal load is determined by the position of the applied
voltage waveform with respect to the current drawn by the load. When voltage and
current are in phase with each other, the power factor is unity and the power for the
load is equal to the product of the applied voltage and load current (P=EI). When the
current waveform lags after the voltage waveform, the load is inductive. Conversely,
when the current waveform leads the voltage waveform, the load is capacitive. In either
case, the power for the load is equal to the product of the applied voltage, load current,
and the angular displacement between the voltage and current waveforms (P=EIcosf).
Nonlinear (nonsinusoidal) loads also have a power factor; however, the power factor
for a nonsinusoidal load reflects harmonic content and not angular displacement.
power factor correction. The addition of a reactive component to offset the angular
displacement of a sinusoidal load. Traditionally, the normal power factor for a facility is
inductive, so the normal correction involves the addition of capacitors to offset the
lagging power factor. The capacitors offset part or all of the inductive reactance,
making the total circuit more nearly in phase with the applied voltage. The power factor
for nonlinear (nonsinusoidal) loads cannot be corrected through the addition of simple
reactive components. Harmonic filters are required to correct the power factor of
nonlinear loads.