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170
Appendix D
O
OCR Abbrev. for optical character recognition. A process by
which a machine can “read” characters printed in a
special standardized font. Data are read by a
photoelectric optical scanner and can be recorded on
magnetic tape or disk. OCR-A and OCR-B are two widely
used OCR fonts.
P
parity (check) Parity checking is the addition of non-data bits to data,
resulting in the number of bits that are set to a “1” being
either always even or always odd. Parity is used to detect
data errors.
PCBA Abbrev. for printed circuit board assembly.
pica A name indicating a monospaced font with a pitch of 10
cpi (and usually 12 points in height). Pica is also used in
typography as a unit of measurement equal to 1/6 inch
.
pin configuration Establishes the physical attachment and protocol
conversion connections for the host interface.
pitch The number of text characters printed per horizontal inch.
Specified in characters per inch (cpi).
See also cpi.
pixel Derived from picture (PIX) ELement. The smallest
displayable picture element on a video monitor or
printable unit. In printing, a pixel is a dot.
point A unit of length in printing and typography, used to
specify type sizes, heights of font characters, etc. There
are 72 points in a vertical inch; thus, one point equals
1/72 inch, or approximately 0.0139 inch. Some examples
of point sizes are:
This is 8 point type. This manual is printed
in 10 point type.
This is 14 point type.
port A channel used for receiving data from or transmitting
data to one or more external devices.
portrait Printed parallel to the short edge of a page.
print mode Font.
proportion, characterSee character proportion.
proportional See font, proportional.
protocol A set of rules or conventions governing the exchange of
information between computer systems, or between a
printer and a host computer. For computer printers, a
protocol is the coding convention used to convey and
print data. A printer protocol includes codes for printing
text and graphics, as well as codes instructing the printer
to perform special operations, and machine-to-machine
communication codes.
See also compatibility and emulation.