User Guide

Hardware Installation
2-20
Memory error checking is supported by two modes, parity check or ECC
(Error Check and Correction). To use memory error check you need 36 bit
SIMM (32 bit data + 4 bit parity or ECC bit). 36 bit parity or ECC SIMMs are
automatically detected by BIOS, however you must enter BIOS setup to
configure the memory for either parity or ECC mode.
Tip: The parity mode uses 1 parity bit for each byte,
normally it is even parity mode, that is, each time the
memory data is updated, parity bit will be adjusted to
have even count "1" for each byte. When next time, if
memory is read with old number of "1", the parity error
is occurred and this is called single bit error detection.
Tip: The ECC mode needs 8 ECC bit for 64 bit data,
because 36 bit SIMM has 4 bit more for parity, the ECC
mode can be supported by two traditional parity SIMMs,
it is no need to have special ECC SIMM. Each time
memory is accessed, ECC bits are updated and
checked by special algorithm, the ECC algorithm has the
ability to detect double bit error and automatically
correct single bit error.