# odd parity

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Related to odd parity: parity bit, Even parity

## odd parity

[′äd ′par·əd·ē]
(computer science)
Property of an expression in binary code which has an odd number of ones.
(quantum mechanics)
Property of a system whose state vector is multiplied by -1 under the operation of space inversion, that is, the simultaneous reflection of all spatial coordinates through the origin.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

## parity checking

An error detection technique that tests the integrity of digital data in the computer. Parity checking adds an extra parity cell to each 8-bit byte of memory, thus creating a nine-bit structure.

In an "even parity" system, a 0 is stored in the parity bit if there is an even number of bits in the byte; if an odd number, a 1 is stored to make the total number of bits even. In "odd parity" systems, the opposite occurs; a 0 parity bit if odd, a 1 parity bit if even to make the total number odd.

Only Good for One-Bit Errors
Each time a byte is transferred, the parity bit is checked. One-bit parity systems will detect if one of the eight bits in the byte has been erroneously switched from 1 to 0 or from 0 to 1. However, it cannot detect a two-bit error, because if two bits in the byte are reversed, the even or odd number remains the same. Error-correcting code (ECC) is a more robust memory checking system (see ECC memory).

Plenty of "NO" Parity Around
There are 12% more memory cells in 9-bit parity chips than there are in 8-bit memory. To shave costs, many computers are built with non-parity memory, and it is truly a miracle that the billions of non-parity computers work as well as they do. See RAID, ECC memory and soft error.
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References in periodicals archive ?
For odd parity, in asymptotic flat and dS spacetime, the perturbation frequency (Re(o>)) becomes smaller and the decay rate ([absolute value of (Im([omega]))]) decreases when b increases.
Caption: FIGURE 2: The effective potential for odd parity gravitational perturbation in asymptotically flat spacetime, with [r.sub.h] = 1, l = 2 (a) and with [r.sub.h] = 1, b = 5 (b).
Caption: FIGURE 3: The temporal evolution of odd parity gravitational perturbation in asymptotically flat phantom BH, with [r.sub.h] = 1, l = 2 (a) and with [r.sub.h] =1, b = 5 (b).
Caption: FIGURE 4: Calculated quasinormal frequencies of odd parity gravitational perturbation for [r.sub.h] = 1 in asymptotically flat spacetime.
Caption: FIGURE 5: The effective potential for odd parity gravitational perturbation in dS spacetime with [r.sub.h] = 1, [r.sub.c] = 10, l = 2 (a) and with [r.sub.h] = 1, [r.sub.c] = 10, b = 5 (b).
Caption: FIGURE 6: The temporal evolution of odd parity gravitational perturbation for dS phantom BH with [r.sub.h] = 1, l = 2 (a), and with [r.sub.h] = 1, b = 5 (b).
Caption: FIGURE 7: Calculated quasinormal frequencies of odd parity gravitational perturbation with [r.sub.h] = 1, [r.sub.c] = 10 in dS spacetime.
Caption: FIGURE 8: The effective potential for odd parity gravitational perturbation in AdS spacetime with [r.sub.h] =1, l = 2 (a) and with [r.sub.h] = 1, b = 1 (b).

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