Memory

What’s Inside an Optane DIMM?

Part of Optane DIMM LogoWith the release of its Cascade Lake family of processors today (formally called the “2nd Generation Intel Xeon Scalable processor”) Intel disclosed more details about its Optane DIMM, which has been officially named the “Intel Optane DC Persistent Memory.”  This DIMM’s architecture is surprisingly similar to an SSD, even to the point of its having error correction and encryption!

The Memory Guy doesn’t generally cover SSDs, but I do cover DIMMs, so this is one of those posts that I could have put into either of my blogs: The Memory Guy or The SSD Guy.  I have decided to put it here with the hopes that it will be easier for members of the memory community to find.

The internal error correction, the encryption, and the fact that 3D XPoint Memory wears out and must use wear leveling, all cause the Optane DIMM’s critical timing path to be slower than the critical path in a DRAM DIMM, rendering the Optane DIMM unsuitable for code execution.  This, and the fact that XPoint writes are slower than its reads, all help to explain why an Optane DIMM is never used as the only memory in a system: there is always a DRAM alongside the Optane DIMM to provide faster Continue reading

Toshiba Decides to Split Off Memory Business

Toshiba Revenue HistoryIn a letter to shareholders released today, Toshiba finally clarified its plans for restructuring the company.  Since January 18 there have been numerous rumors that Toshiba planned to spin its memory business off or sell it outright.  Today’s letter indicates that this hasn’t been decided yet.  In fact, other than to call a late March shareholder vote and to reveal a restructuring, the letter discloses extraordinarily little.

In a nutshell Toshiba has decided to isolate the memory business (including the SSD business but not the HDD and image sensor businesses) into a separate wholly-owned subsidiary.  There was no mention of either the recently-shrinking Discrete business or the System LSI business, which has been in a steady decline for the past decade.  Click on this post’s graphic to see how each of the company’s semiconductor businesses has been doing.

The intent appears to be to groom the subsidiary to be spun off or sold, but this has not been expressly stated.  Instead Toshiba simply states that: “The Company is still considering various structures with a view to an injection of third-party capital.”

The letter reiterates Toshiba’s prior position that the memory business Continue reading

What is a Content-Addressable Memory (CAM)?

This is not the kind of CAM the post is about!What is a Content-Addressable Memory (CAM)?  The Memory Guy decided to post this after having recently run across a very strange web post HERE that erroneously inferred that CAM chips from NEC could be a threat to NAND-based SSDs.  The article was based on a press release from NEC and Tohoku University that can be read HERE.

It’s not at all surprising that the release was misunderstood – it’s very awkwardly written:

The new CAM utilizes the vertical magnetization of vertical domain wall elements in reaction to magnetic substances in order to enable data that is processing within the CAM to be stored on a circuit without using power.

Continue reading