Unheard-of computer company All Computers is suing Intel for $500 million over the company's alleged infringement of a circuit design patent. All Computers has also asked for a permanent injunction against Intel.

The short complaint claims that Intel's Pentium II processor infringes a circuit design patented by All Computers under US patent 5,506,981.

That patent, titled "Apparatus and method for enhancing the performance of personal computers", covers "an accelerator board for use in replacing the microprocessor of a slow speed system board with a microprocessor operating at a higher clock speed". The system clock in a chipset runs at a slower speed than the processor core clock, which is up to 3.4GHz in some of Intel's chips, said Kevin Krewell, editor in chief of the Microprocessor Report. A phase lock loop is responsible for synchronising the system clock and the core clock so the chipset works properly, he said.

In the past, the phase lock loop could only work with core clocks that were whole multiples of the system clock, but All Computers founder Mers Kutt developed a circuit design that allowed chip designers to run core clocks at fractional multiples of the system clock, claims All Computers' lawyer Edward F. O'Connor. Kutt is noted as the man that introduced the world's first personal computer, the MCM-70, in 1973, says a press release by the lawyer firm.

The patent itself was filed on 1 October 1993 and was granted over eight years ago on 9 April 1996. However, O'Connor explains the delay in filing a suit against Intel by claiming that All Computers only recently realised that Intel had used the technology.

The Pentium II has not been Intel's primary desktop microprocessor for several years, but All Computers believes the Pentium III processor may also infringe its patent. It is not completely sure, however, O'Connor said. The company has yet to determine if the Pentium 4, Intel's current desktop processor, infringes on the patent.

All Computers case is not helped by its very low profile. Its website at www.allcomputersinc.com was only registered in November last year and redirects to Mers Kutt's home site which features only a single, very limited webpage. All Computers has not released a product for about ten years, O'Connor admitted. The company sold a product called the All Chargecard in the 1980s that added memory to IBM PCs.

Intel lawyers have so far refused to comment, saying that they haven't seen the lawsuit.

The merits of this case probably won't be fully known until the judge conducts a Markman hearing, or a reading of the patent and a definition of the terms within that patent as they apply to the products in this case. The parties in the lawsuit can expect to reach the Markman hearing in about six months.

Intel has been involved in numerous patent lawsuits over the last few years. It recently settled outstanding litigation with Intergraph over patents related to the Itanium processor as well as Intergraph's Clipper memory management technology. Last year, it settled several patent claims with Via Technologies over chipset designs.