Microsoft KB Archive/67366

‘PARITY CHECK’ and ‘PARITY ERROR’ Message Description PSS ID Number: Q67366 Article last modified on 09-16-1993 PSS database name: O_MSDOS

MS-DOS

= SUMMARY =

You may receive the following error message on your screen:

PARITY CHECK 1

and then your machine may stop responding (hang).

The PC has special circuitry that continually checks the memory (RAM) for anomalies. Each time memory is read or written to, a “sanity check” is made. If this check fails, then a failure to properly store the information in memory has occurred. In this event, the circuitry interrupts the system and displays a “PARITY ERROR” message.

= MORE INFORMATION =

Memory chips on a typical PC are arranged in banks of nine. The first eight chips serve as addressable memory, and the ninth chip holds the parity bits for the previous eight. In this configuration, there is one parity bit. In board memory, this parity bit is set for each byte of memory in such a way that the sum of the eight bits plus the parity bit is always odd. If the system detects an even sum, a “PARITY CHECK 1” error occurs. In memory on an expansion board, the message “PARITY CHECK 2” is displayed.

Static electricity is a common cause of parity errors. If a computer comes in contact with a static charge, the charge may “zap” the computer’s memory.

Additional reference words: noupd

Copyright Microsoft Corporation 1993.