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Glossary of Data Communications Terms
Courtesy Enterprise-Wide Computing, Inc.
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Term:
parity
Definition:
The quality of sameness or equivalence, in the case of
computers usually referring to an error-checking procedure
in which the number of ones ('1's) must always be the
same--either even or odd--for each group of bits
transmitted without error. If parity is checked on a
per-character basis the method is called vertical
redundancy checking, or VRC; if checked on a block-by-block
basis, the method is called longitudinal redundancy
checking, or LRC. In typical modem-to-modem
communications, parity is one of the parameters that must
be agreed upon by sending and receiving parties before
transmission can take place. Types of parity are shown
below. Related terms include ASCII, byte, bit, parity
bit,
parity check, and parity error.
Even parity: The
number of 1s in each successfully transmitted set of bits
must be an even number.
Odd parity: The number of 1s in
each successfully transmitted set of bits must be an odd
number.
No parity: No parity bit is used.
Space parity:
A parity bit is used and is always set to zero (0).
Mark
parity: A parity bit is used and is always set to one (1).
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