LONDON — Processor technology licensor ARM Holdings plc has disclosed that in September 2006 it intervened in patent litigation between Technology Properties Limited Inc. (TPL) and certain companies in the Fujitsu, Matsushita, NEC and Toshiba groups of companies and became a defendant in their court cases.

Law suits against these companies, originally filed in October 2005 in the United States District Court for the Eastern District of Texas (Marshall Division), alleged the companies infringed U.S. Patents Nos. 5,809,336; 5,784,584 and 6,598,148.

All of the defendants were ARM licensees and as part of the preliminary infringement contentions, filed in July 2006, it was alleged that certain ARM technology infringes a single claim in the 584 patent.

In September 2006 ARM filed a motion to intervene in the litigation and that motion has been granted and as a result ARM is now a defendant in the law suit, the company said in a statement accompanying its third quarter financial results.

TPL formed an alliance with Patriot Scientific Corp. in 2005 and pooled processor technology patents together in something they call the Moore Microprocessor Patent (MMP) portfolio, named after Charles H. Moore, chief technology officer of TPL Group, who is credited with inventing the Forth software programming language and is known for his work in the 1980s on stack-based microprocessors.

The MMP portfolio includes seven U.S. patents, as well as their European and Japanese counterparts, which Patriot (San Diego, Calif,) and TPL Group (Cupertino, Calif.) have said they consider fundamental to the design of modern microprocessors, microcontrollers and system-on-chip devices. Three of the patents are: U.S. Patent 5,809,336, which covers the separate clocking of a CPU and its I/O; U.S. Patent 6,598,148, which covers the use of multiple cores and embedded memory; and U.S. Patent 5,784,584, which covers fetching multiple instructions. Patriot and TPL have licensed a number of companies to use the MMP portfolio, most noticeably leading processor vendors Intel Corp. and Advanced Micro Devices Inc.