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Glossary - 8
PC Card. A plug-in expansion card for laptop computers and other devices, also called a PCMCIA card. PC Cards are
85.6mm long x 54 mm wide, and have a 68 pin connector. There are several different kinds:
Type I; 3.3 mm high; use - RAM or Flash RAM
Type II; 5 mm high; use - modems, LAN adaptors
Type III; 10.5 high; use - Hard Disks
PCMCIA. Personal Computer Memory Card Interface Association. See PC Card.
Percent Decode. The average probability that a single scan of a bar code would result in a successful decode. In a
well-designed bar code scanning system, that probability should approach near 100%.
PING. (Packet Internet Groper) An Internet utility used to determine whether a particular IP address is online. It is used
to test and debug a network by sending out a packet and waiting for a response.
Print Contrast Signal (PCS). Measurement of the contrast (brightness difference) between the bars and spaces of a
symbol. A minimum PCS value is needed for a bar code symbol to be scannable. PCS = (RL - RD) / RL, where RL
is the reflectance factor of the background and RD the reflectance factor of the dark bars.
Programming Mode. The state in which a scanner is configured for parameter values. See Scanning Mode.
Q
Quiet Zone. A clear space, containing no dark marks, which precedes the start character of a bar code symbol and
follows the stop character.
QWERTY. A standard keyboard commonly used on North American and some European PC keyboards. “QWERTY”
refers to the arrangement of keys on the left side of the third row of keys.
R
RAM. Random Access Memory. Data in RAM can be accessed in random order, and quickly written and read.
Reflectance. Amount of light returned from an illuminated surface.
Resolution. The narrowest element dimension which is distinguished by a particular reading device or printed with a
particular device or method.
RF. Radio Frequency.
ROM. Read-Only Memory. Data stored in ROM cannot be changed or removed.
Router. A device that connects networks and supports the required protocols for packet filtering. Routers are typically
used to extend the range of cabling and to organize the topology of a network into subnets. See Subnet.