Clarification of Answer by
denco-ga
on
15 Apr 2003 10:20 PDT
Howdy idiaz!
A good question, as there is non-ECC registered memory, as shown at
the Viking InterWorks web site.
http://www.vikingcomponents.com/products/t4.asp
To cut to the chase, the 4ALL Memory web site has:
http://www.4allmemory.com/index.cfm?fuseaction=faq.details&faq_id=98
"How can I tell if I have ECC or non-ECC memory?"
"For SDRAM or DDR memory, just count the number of small black chips
on one of your existing memory modules. If the number of chips is even
then you have non-ECC. If the number of chips is odd then you have ECC."
ECC Technologies, Inc. has an extensive ECC FAQ.
http://members.aol.com/mnecctek/faqs.html
"In most cases, such as ... semiconductor memory, errors must be detected
and corrected "on-the-fly", or, at the same rate as data is being read from
the disk. The "on-the-fly" performance requirement usually means the error
correction implementation must be done in digital logic (hardware)."
With this information, and some of the below, it looks like Error Correction
(or Correcting) Code (or Error Checking and Correcting, etc.) or ECC, is
chip-based, and the "odd" chip contains the code/logic.
It appears your thoughts on the "small chips" being the "registers" might
be on target, as described by A1 Electronics.
http://www.a1-electronics.co.uk/Memory/Questions_answered.shtml
"What is "registered SDRAM"?"
"This is the SDRAM version of a buffered module. All memory must be buffered.
Buffer logic chips clean up the signals on a DRAM module, they provide a small
buffer or cache where data can be held for 1 clock cycle prior to being written
to the DRAM cells."
Your "small chips" could be the buffer logic chips mentioned above.
For more information, there are the following:
MemoryX's web site provides some nice term definitions.
http://www.memoryx.net/generic-memory.html
"ECC - Error correcting code. Logic designed to detect and correct
memory errors. Memory modules designed with 72 bits of memory support
the motherboard's ECC function."
"Registered - Registers delay memory information for one clock cycle
to ensure all communication from the chipset is collected by the clock
edge, providing a controlled delay on heavily loaded memories.
"DIMM - Dual in-line memory module. This physical property describes a
module with signal and power pins on both sides of the board."
"Unbuffered - This is the most common configuration for memory. These
modules do not use any supporting TTL logic."
InfoHQ.com has an informative ECC primer.
http://www.infohq.com/Computer/ecc-dram.htm
"What is ECC SDRAM? ECC (error correction code) SDRAM is memory that is
able to detect and correct some SDRAM errors without user intervention.
ECC SDRAM replaced parity memory which could only detect, but not correct,
SDRAM errors."
Search strategy
registered non-ecc
://www.google.com/search?q=registered+non-ecc
ECC "how does it work"
://www.google.com/search?q=ECC+%22how+does+it+work%22
"what is ecc"
://www.google.com/search?q=%22what+is+ecc%22
I hope this clarification aids you in identifying your memory.
Looking Forward, denco-ga
