A chapter in the Stratosphere saga closed recently when SanDisk settled legal proceedings with two former msystems’ employees. Apparently in exchange for $4 million, Amir Ban and Simon Litsyn dropped their claims against the company and Dov Moran. Some details were released on the Hebrew site NRG. [a machine translation is included at the end of this post]
The settlement was reached via arbitration and details will remain private.
The reference to Stratosphere, as another name for x4, caught my attention. I have long suspected that x4 was somehow connected to Stratosphere. Although Dov denied it, it seems Ban et al had a different opinion. Curiously, both may be right.
In any case its past history now.
This week I decided to dig back through my Stratosphere notes. After review, I am more convinced than ever that x4 is a related implementation of Stratosphere.
That said, x4 is a slightly different beast than Stratosphere. Each seems to have its own touchstone patent. Same inventors, but different Assignees. Different emphasis.
Whereas the Stratosphere technological is a breakthrough in physics, x4 appears to be primarily a breakthrough in signal processing algorithms. A related insight, but different emphasis.
This is interesting as it sheds light on aspects x4 never discussed publicly to my knowledge. x4 has been billed as a whole new way of looking at the physics of NAND itself. Now we may have a few hints.
A word of warning. Please don’t take my interpretations too seriously. I have done my best, but beyond 3 dimensions, I struggle. Both Stratosphere and x4 live in a world where very advanced math meets cutting edge memory physics. A 16-dimensional rectangular grid, embedded within a 16 dimensional hypercube is nothing for these guys.
Stratosphere was conceived in 2000 as a collaboration between msystems and the Tel Aviv University. Key folks were Amir Ban from msystems, and Professor Simon Litsyn from the university. Professor Litsyn’s doctoral students Idan Alrod and Eran Sharon were also involved.
The breakthrough apparently came where information theory meets the physics of flash.
The key Stratosphere patent appears to be U.S. patent #6,469,931, “Method for Increasing Information Content in a Computer Memory.” This patent was applied for in 2001 and issued in 2002. Inventors are listed as Amir Ban, Simon Litsyn and Idan Alrod. Assignee is msystems.
The key idea is that groups of flash memory cells can store information above and beyond the information stored in the flash memory cells themselves. With a few twists, a top-up in memory capacity is possible for “free.” The image below, from the patent, illustrates a schematic description of a two-dimensional optimal encoding scheme.
One example given in the patent is for single level cell flash memory. Today, 16 cells of SLC NAND can store 16 bits of information. Using the Stratosphere approach, 20 bits of information can be stored using the same 16 cells of SLC, for a 25% gain in capacity.
Capacity gains increase as the bits/cell increase. In other words 2 bits/cell MLC is better than SLC, and 3 bits/cell MLC better yet, and so forth.
According to Amir Ban, a prototype of Stratosphere was developed and this Stratosphere technology was shown to a very-interested Toshiba in 2004, which was “fascinated” and sought to enter negotiations over the technology.
A note on Amir Ban, who must be quite the character as well as a rather smart guy: in his spare time he writes world-class computer chess programs. Along with fellow chess lover Shay Bushinsky, he is responsible for Deep Junior, the computer chess program that played Gary Kasparov to a draw in 2003 .
Amir Ban is on the left and Shay Bushinsky on the right in the photo below.
In June 2006 msystems’ CEO Dov Moran announced x4, claiming the the technology would prove to be the first viable 4 bit per cell flash storage solution, which doubled the storage capacity of current MLC solutions at roughly the same cost.
Dov explained that msystems had been working on x4 for 5 years in secret. The same time frame as Stratosphere. At its one and only msystems’ analyst day, the detailed x4 presentation was made by msystems’ chief scientist, Future Technologies Group, Simon Litsyn.
This is the same Professor Simon Litsyn from Tel Aviv University, that developed Stratsphere with Amir Ban and the same Simon Litsyn that is currently splitting the $4M settlement from SanDisk. Personally I hope that SanDisk finds a way to entice Mr. Litsyn into working with them (if he isn’t already) as he seems to have proven he has the right stuff.
Whereas the Stratosphere technology is a breakthrough in physics, x4 appears to be primarily a breakthrough in signal processing algorithms. A related insight, but different emphasis.
The key x4 patent appears to be U.S. patent #7,023,735, “Method for Increasing the Reliability of a Flash Memory.” This patent was applied for in 2004 and issued in 2006. Inventors are listed as Amir Ban, Simon Litsyn and Idan Alrod. Assignee is Ramot at Tel-Aviv University.
The main idea is that by programming flash memory using reference voltages, fractional reference voltages, and redundancy bits, the reliability of info stored in MLC flash memory can be improved. Again, just like for Stratosphere, each memory cell is not considered only by itself. Reliability can be improved by taking advantage of the frame of reference offered by groups of memory cells.
The patent illustration below illustrates the voltage bands of an eight level flash cell including fractional reference voltages.
x4 has been described as a system solution, including a special x4 chip, a special very complex x4 controller, and special x4 software. All are essential. This patent #7,023,735 seems to address the issues of signal processing algorithms and hence the x4 controller and software.
I really don’t have a sense of the x4 chip itself, other than no special equipment is purportedly required for fabrication and that without the proper x4 controller the chips themselves are considered worthless. The x4 chip itself has never been described along the lines of the Stratosphere technology as far as I am aware, but the x4 controller fits pretty much exactly.
While the 735 patent is theoretical, the x4 controller is very real. Working prototypes exist. It may take over a million gates, but it works purportedly as advertised. As Simon Litsyn said in 2006, when Dr. Boaz Eitan questioned x4:
“I don’t know how I can respond to such comments, but I’m prepared to say that we laughed out loud at his comment. We had the product sitting on the desk, and functioning like clockwork.”
SanDisk x4 Roadmap
At the recent 2008 analyst day, SanDisk described its NAND roadmap, illustrated below.
x4 is still on schedule for a 2009 introduction at 43nm as a 64G chip. Same schedule as a year ago.
43nm is the technology node, and 2009 is the year, where SanDisk plans to get serious about moving beyond 2 bits per cell. It will be interesting to see how the competition responds.
In 2008 SanDisk will begin the production of 3 bits/cell at 56nm, but the majority of the production in 2008 will remain 2 bits per cell technology. This is because 43 nm 2 bits/cell is lower cost than 56nm 3 bits/cell.
2009 is when 43nm 3 bits/cell technology will become a significant driver of SanDisk production output. About 50% of total bit production in 2009 is projected to be 3 bits/cell 43nm technology. 2 bits/cell production will be less than 3 bits/cell production. x4 production in 2009 will be less than 2 bits/ cell production.
Basically 2009 will the year of introduction of x4. No comments were made about 2010, but x4 is projected at 3xnm.
My suspicion is that SanDisk’s engineering controller resources are currently focussed on SSDs @ 2 bits/cell and x3 @ 3 bits/cell. Next up will be tuning x4, as per schedule.
Notably absent from 2008 Analyst day discussion was any commentary related to x4 cooperative development with either Toshiba or Hynix. msystems had been working with both. My guess is that the dynamic has changed with SanDisk.
**** machine translation of 2008 NRG article below ****
[This translation was passed along by an acquaintance]
Compromise between SanDisk to the keys of the disk on key Ban and Litsyn, that developed drives of memory of the flash that are small when worked whether M-systems, will receive 4 million dollar in the frame of agreement of thaw that is secret. In return they will erase the claim against SanDisk
At the start of this week was signed agreement of compromise between the company SanDisk, that acquired M-systems, and Amir Ban and professor ‘ Shimon Litsyn, that developed drives of memory of flash are small ) disk on key (when worked with M-systems. By right of the use in this technology is sold if M-systems SanDisk in exchange for 1.5 billion dollar. According to agreement of thaw, Ban and Litsyn will receive about 4 million dollar. In return, is erased the claim that served Ban against parent company M-systems and founder of the company Dov Moran in the assertion of question violated their obligation towards him Onicso to themselves you are profitable the invention. The agreement itself will not be served for approval of the court, inasmuch as that will be prepared secret. The agreement was obtained in the frame of procedure
Ban was project manager ” stratosphere ” of M-systems, that his different name pursuant for 4x and that business in the development of the disk on key. According to him, if M-systems obligated to establish a company to the project, but after became clear her that the project of winner to the great success and that the company Toshiba is impressed from him very – changed her mind and requested to the asset to herself every fruits of the project. Accordingly sued Ban is a third from the rights that produced from the invention if M-systems and has her shares. Also concluded age, that joined the project in the stage more late, served a claim against if M-systems, SanDisk, Amir Ban and Dov Moran.
**** Marker.com from 2004 below ****
Former worker claims M-Systems owes him rights in Stratosphere technology
10.10.2004 | 14:47
Eynav Ben Yehuda
A former employee of M-Systems (Nasdaq:FLSH) claims to essentially be one of the company’s founders, having held high-ranking positions there in the 12 years almost since its establishment. In practice M-Systems was launched as a startup in 1989 and Amir Bann joined in 1992, but he claims to have played a key role in making it a half-billion dollar company.
Bann quit in October 2003 but claims he is owed 33% of the rights in a joint company that M-Systems agreed to establish. He is now suing at the Tel Aviv Labor Tribunal for those rights.
Not so, M-Systems responded in a letter to Bann’s lawyer, before the suit was filed: there was no agreement.
From 2000, writes Bann’s lawyer Itzhak Goldberg, Bann and others had been engaged in developing a technology called Stratosphere. M-Systems had shown no interest in it. Nor did it provide financing for development, which was collected from external investors.
After resigning, Bann suggested M-Systems and the Stratosphere inventors, including himself, establish a joint company that would commercialize the patented technology. M-Systems was persuaded and asked Bann to prepare a business plan, writes the lawyer.
The resultant business plan incorporated a plan for the distribution of shares and rights in the putative company. (Bann did not append his business plan to his lawsuit, because it contains confidential information, his lawyer wrote.)
In late December M-Systems decided to accept the plan, Bann claims, and he and others made plans for the future accordingly. For one thing M-Systems asked him to delay leaving the company and he agreed to accept a half-time position.
Under the agreement he claims to have with M-Systems, Bann said he should have received 33% of the shares in the joint company.
Believing the joint company would be established, Bann claims, he acted to recruit manpower, to update and execute the business plan and interest venture financiers, and mainly continued to develop the technology, resulting in a prototype.
To create the prototype, Bann developed a new technology after December 2003, to increase the memory capacity in the flash compartment at relatively low cost. Bann notes that he developed the technology for the new company, not for M-Systems itself, based on the agreement he says was reached in December 2003.
Meanwhile, great interest was sparked in the new technology, Bann continues, adding that M-Systems has business ties with Toshiba. And the technology was presented to Toshiba, which was fascinated. It sought to enter negotiations with M-Systems over the technology, Bann claims.
At that point, M-Systems acted in bad faith and cancelled the agreement, claims Bann, and sought to deprive him of his rights.
Contacted by attorney Goldberg in mid-2004, M-Systems responded that the claims represented a distortion of reality and said it rejected Bann’s claims. Not only did M-Systems not cancel or breach an agreement, it stated in its letter, which Bann appends to his lawsuit: there had been no agreement. Nor had Bann been a founder, having joined the company well after its establishment. Also, M-Systems claims to have fully financed the development of Stratosphere by Bann and others.
M-Systems agreed to consider establishing a joint company, it says, but never actually agreed to do so, and the business plan Bann presented did not constitute any such agreement. While M-Systems considers spinoffs from time to time, it rarely carries out the plans, it added.
Obviously a subject as weighty as establishing a joint company to develop a new technology would be thoroughly covered by agreements, M-Systems pointed out, which was not the case here. And Bann’s claims to ownership over the technology contravene the terms of his employment agreement, which he did not formally terminate in October 2003 as claimed.