The reason why ex-IBM executive Mark Papermaster can’t work for Apple is because Apple and IBM compete in microprocessors for iPod and iPhones. That’s what the judge deciding where Papermaster can work – in view of his non-compete – said in his 28-page opinion explaining why IBM was able to get the preliminary injunction that yanked him out of Apple five days after he started there as head of iPod and iPhone hardware development.

The opinion was only made public after IBM and Apple made sure it was sanitized and hangs on the judge's apprehension that Papermaster, IBM's top Power chip jockey in whom all of IBM's most treasured trade secrets and strategic information are said to repose, will inevitably - if inadvertently - use them to advance Apple's fortunes to IBM's "irreparable harm."

He can't help but use them since all he's done for the last 26 years is suckle at IBM's tit.

The opinion also hangs on the fact that Apple CEO Steve Jobs told the New York Times that PA Semi, the start-up it bought that designed a low-power Power chip under a license from IBM, "would be used to build system-on-chips for the iPhone and iPod Touch."

And that IBM told him that "Within the last 18 months, IBM has developed technology that is compatible with consumer electronics products such as cell phones and MP3 players," citing some newfangled digital storage technology that enables MP3 players like the iPod to store a half-million songs or 3,500 films with lower-power output.

District Court Judge Kenneth Karas says he "recognizes that IBM doesn't sell MP3 players or cell phones that compete with the iPod or the iPhone. But, IBM does sell the microprocessor technology that provides the electronic brains for those products and competes for that business. To profit from the manufacture and sales of such microprocessors, IBM relies heavily on its ‘Power' architecture and has employed Mr. Papermaster as its top expert in the development and application of that technology."

Either IBM has secretly rejigged the Power like PA Semi did for cell phones or it's actually talking about IBM Microelectronics' foundry business which makes chip components for third parties.

And of course nobody knows what PA Semi is up to. It's unclear whether it's still working with the Power chip or whether it's deploying its skills on the ARM, the chip Apple currently uses in the iPod and iPhone so Apple can have an ARM of its very own. Whatever it's doing, Apple doesn't have a chip of its own yet.

However, the judge writes that "Apple announced its intention to have PA Semi develop the very type of product that IBM sells to the market generally, and would like to sell to companies like Apple."

What product that is exactly is unstated.

The court accepts that Papermaster won't be managing PA Semi or developing chips for the iPod or iPhone if he goes to work for Apple but it's alarmed that his job "will require him to make decisions about what type of microprocessor technology to use in these products" and that he will "draw upon his IBM experience in making those decisions."

Too much knowledge is obviously a dangerous thing.

Judge Karras points out that to get a preliminary injunction the court has to be convinced that complainant will ultimately win his case. He's put the trial on an expedited schedule.