[rescue] What is a RIMM?

[Phil Stracchino]

Mike Nicewonger wrote:
> On Apr 22, 2006, at 1:43 PM, Patrick Giagnocavo wrote:
>>On Sat, 2006-04-22 at 13:37, Geoffrey S. Mendelson wrote:
>>
>>>I was given a P4 based computer with RIMM memory. I've never seen 
>>>one, and have never seen them for sale here. Are they compatible
>>> with other memory such as DDR or SDRAM DIMMS?
>>
>>RAMBUS.  I think a RIMM is actually some kind of non-memory that goes 
>>in memory slots and functions as a terminator, like on a SCSI bus.
> 
> RIMM like DIMM.
> 
> Rambus Inline Memory Module.

What he said.  AKA RDRAM.

No, they are not compatible, either electrically or physically.  RAMBUS
memory is a high-speed memory technology like DDR, but more expensive
than DDR and arguably possessing some serious technical drawbacks.  As I
recall it, RAMBUS memory has the capability for high throughput on
sustained sequential reads and writes, compared to SDRAM, but has higher
latency than either SDRAM or DDR on random reads and writes.  (I have a
friend who's something of an expert on the subject, but he's AFK right now.)

There are also some nasty legal wrangles involving associated
technology, including but not limited to RAMBUS concealing patents on
DDR and SDRAM technologies from JEDEC while providing the technologies
in question to JEDEC for inclusion in proposed standards, then revealing
the patents after the standards had been finalized and announced.
Several lawsuits filed by RAMBUS in .EU courts were summarily dismissed
after defendants including Infineon were able to show that RAMBUS had
knowingly shredded relevant evidence.  The FTC is currently pursuing an
antitrust case against RAMBUS by "deliberately engaging in a pattern of
anti-competitive acts and practices that served to deceive an
industry-wide standard-setting organization, specifically, not
disclosing that it was in the process of seeking patents related to the
proposed standards."

Relevant URLs include:
http://www.pcworld.com/news/article/0,aid,109132,00.asp
http://www.internetnews.com/bus-news/article.php/3487396
http://www.internetnews.com/bus-news/article.php/3312411
http://www.theregister.co.uk/2004/02/18/europe_to_revoke_rambus_memory1/


Currently, the RAMBUS technology is pretty much moribund, both because
no-one wants to touch the technology due to liability and licensing
issues around the lawsuits, and because DDR (and especially DDR2) offers
considerably higher memory performance at lower cost.


-- 
 Phil Stracchino                     Landline: 603-886-3518
 phil.stracchino at speakeasy.net         Mobile: 603-216-7037
 Renaissance Man, Unix generalist, Perl hacker, Free Stater