Glossary P
Centillion 1200N ATM Switch User Manual B-55
NTP 297-8103-903
PBX
Private Branch eXchange: PBX is the term given to a device which provi des private
local voice switching and voice-related services within the private network. A PBX
could have an ATM API to utilize ATM services, for example Circuit Emulation
Service.
PC
Protocol Control: Protocol Control is a mechanism which a given application
protocol may employ to determine or control the performance and health of the
application. Example, protocol liveness may require that protocol control
information be sent at some minimum rate; some applications may become
intolerable to users if they are unable to send at least at some minimum rate. For
such applications, the concept of MCR is defined. Refer to MCR.
PCM
Pulse Code Modulation: An audio encoding algorithm which encodes the
amplitude of a repetitive series of audio samples. This encoding algorit hm converts
analog voice samples into a digital bit stream.
PCMCIA
Personal Computer Memory Card International Association (an awful mouthful)
standardizes credit-card size packages for memory and input/output (modems,
LAN cards etc.) for computers, laptops, palmtops, etc. There are three physical
standard for PCMCIA cards-Type 1,2,3 and undefined standard called type 4,
which only Toshiba has at this moment.
PCO
Point of Control and Observation: A place (point) within a testing environment
where the occurrence of test events is to be controlled and observed as defined by
the particular abstract test method used.
PCR
Program Clock Reference: A timestamp that is inserted by the MPEG-2 encoder
into the Transport Stream to aid the decoder in the recovering and tracking the
encoder clock.
PCR
Peak Cell Rate: The Peak Cell Rate, in cells/sec, is the cell rate which the source
may never exceed.