odd parity

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.

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).