A patent granted in 1994 to Compaq for an adaptation of its 16-bit EISA system bus architecture -- which Compaq co-created, but which was already becoming outmoded by 1994 -- is among four patents amended last Thursday to Hewlett-Packard's list of alleged infringement subjects, in its ongoing patent battle against oncoming competitor Acer.

Patent #5,353,415, for "Method and apparatus for concurrency of bus operations," explains how a computer's cache interface logic can be used to make posting cycles that would normally wait for one another in sequence, make room for one another in alternating concurrency. The technology is an outgrowth of Compaq's early work in pioneering the first 16-bit expansion busses.

During the late 1980s, Compaq was the champion of what was then technology's most gripping market battle: the duel with IBM to establish the next x86 expansion bus. Compaq was EISA's principal designer and champion, and had industry-wide support because it promised to be the logical descendant of Industry Standard Architecture. What's more, it had the backing of Microsoft.

IBM, meanwhile, moved forward with MicroChannel Architecture for its PS/2 series computers. It was not downwardly compatible with ISA, though it was considered more revolutionary. But like a certain standards battle going on in today's marketplace seems to be shaping up, neither side won as a third option (PCI-Express) eventually won the day.

HP acquired Compaq's patent portfolio along with the company in 2001. Meanwhile, Acer was a producer of EISA bus computers up until at least the early 1990s. Residue of EISA technologies still exist in modern systems, probably including Acer's, especially with respect to the partitioning of disk drives for downward compatibility.

But exactly how Acer may be infringing upon this patent today, to the extent that HP requests an injunction against importing its PCs here from Taiwan, may be a most interesting explanation - assuming the case ever reaches a courtroom.

HP's amended complaints add to what has become a daily, if not twice daily, event: a now-constant cycle of IP infringement lawsuits, most alleging willful infringement in order to qualify for treble damages. Such suits may be being filed now in order to avoid being invalidated by proposed bicameral Congressional legislation that could potentially strike the treble damages provision from US code, as well as raise the bar substantially for claimants.

Also on HP's amended list of complaints on Thursday were: a 2004 patent granted to HP after Compaq filed for it in 1999, for a power conservation method for laptop computer displays; a method filed by Compaq in 1996 for controlling system temperature based on readings taken from multiple zones inside the computer, and averaged together; and a 1998 Compaq filing awarded to HP in 2005, for automatically detecting screen resolution from a display controller by assessing one of its pixel clock measurements.

Quite possibly, many of the technologies for which Compaq originally filed those patent applications in the previous decade, may have become at least partly outmoded in the modern era of platform-based notebook computers. But HP may yet have an opportunity to state its case in further detail, and in so doing, perhaps resolve the issue of why Acer appears to be the sole infringer - at least for now.