Rambus has sued one of its own supporters, Hitachi, over allegations that the Japanese memory maker ripped off four Rambus "synchronous memory" patents. The case centres on four patents filed in 1990 by Rambus' co-founders. The patents cover 141 technologies relating to the way synchronous DRAM chips and inline memory modules work, how they interface with the host CPU. Pretty fundamental stuff, in other words, and, interestingly, nothing to do with the memory technology for which Rambus is best known. "This does not relate to Rambus components," Rambus VP of marketing, Avo Kanadjian, told EE Times. Rambus has been pursuing the alleged violation for some time. Its claims were brought to Hitachi's attention last year, and a meeting scheduled to discuss them. Hitachi clearly wasn't having any of it and decided not to show up. So now Rambus is suing. Hitachi isn't the only company Rambus has raised its ownership of key SDRAM technologies with -- "We are in negotiations with companies that use this technology, but it would be inappropriate to comment further on those negotiations, since they are confidential," said Kanadjian -- but it does appear to be the first to have decided to take a hostile approach to Rambus. With the patents covering some very basic features of how modern CPUs talk to memory, it would be surprising if Rambus hasn't also been talking to the likes of Intel and AMD, though the company refuses to name any of the parties it's been in negotiations with. Hitachi is currently evaluating the details of Rambus' suit. ®