IBM AT 5170 Technical Reference page 472

nano (n). Prefix 0.000,000,001.
nanosecond (ns). 0.000,000,001 second.
negative true. Synonym for active low.
negative-going edge. The edge of a pulse or signal changing in a
negative direction. Synonymous with falling edge.
non-retum-to-zero change-on-ones recording (NRZI). A
transmission encoding method in which the data terminal
equipment changes the signal to the opposite state to send a
binary 1 and leaves it in the same state to send a binary O.
non-return-to-zero (inverted) recording (NRZI). Deprecated
term for non-retum-to-zero change-on-ones recording.
NOR. A logic operator having the property that if P is a
statement,
Q
is a statement, R is a statement, ... , then the NOR of
P,
Q,
R, ... is true if all statements are false, false if at least one
statement is true.
NOR gate. A gate in which the output is 0 only if at least one
input is 1.
NOT. A logical operator having the property that if P is a
statement, then the NOT of P is true if P is false, false if P is true.
NRZI. Non-retum-to-zero change-on-ones recording.
ns. Nanosecond; 0.000,000,001 second.
NUL. The null character.
null character (NUL).
A control character that is used to
accomplish media-fill or time-fill, and that may be inserted into or
~
removed from, a sequence of characters without affecting the
meaning of the sequence; however, the control of the equipment
or the format may be affected by this character.
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