Glossary–9
nS Nanosecond.
NVFU Direct Access Vertical Format Unit. See also DAVFU.
NVRAM Abbrev. for non–volatile random access memory. This storage is
permanent, in the sense that information is not lost when the
printer is powered off.
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.
Ohm A unit of measurement for electrical resistance.
P
PA Program Attention. Used in applications programs.
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.
PC Personal Computer.
PCBA Printed Circuit Board Assembly.
pel The smallest element of a physical medium that can be
independently assigned color and intensity. Pels per inch is often
used as a measurement of presentation granularity. Synonymous
with picture element, pixel.
PI Abbrev. for Paper Instruction: a physical hardware I/O line used
in conjunction with the eight data bit lines. When PI is set high, it
indicates that the eight data bits are interpreted as a paper motion
command instead of printable data.
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.
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