Imagination Technologies has placed its patents row with Apple on a formal footing, confirming to the City that it has opened a dispute resolution process because—it says—attempts to settle a licence and royalty deal with the iPhone maker remain at a standstill.

In April, the British chip design company hinted that a IP row was brewing by claiming that Apple's own chip designs might breach Imagination Technologies' patents.

The company, which derives roughly half of its revenues from a licensing deal from Apple, learned last month that the Tim Cook-run multinational planned to ditch the UK-based semiconductor supplier by 2019.

Shares in Imagination collapsed nearly 70 percent on the London Stock Exchange following Apple's decision to rip up its contract with the firm and go it alone with its own "independent graphics design."

Since then, the two companies have been locked in talks over "potential alternative commercial arrangements for the current licence and royalty agreement."

In a trading update on Thursday, Imagination said that, to date, no "satisfactory progress" had been made with Apple. It added:

Imagination has therefore commenced the dispute resolution procedure under the licence agreement with a view to reaching an agreement through a more structured process. Imagination has reserved all its rights in respect of Apple’s unauthorised use of Imagination’s confidential information and Imagination’s intellectual property rights.

The British firm, by opening a dispute resolution process, appears to be hoping to reach a new deal with Apple that stops short of legal action. Intriguingly, Imagination has also decided to sell-off chunks of its business to focus more heavily on its graphics chip division. It plans to dispose of its embedded processor tech MIPS and Ensigma mobile connectivity divisions—two core units which just a year ago were ring-fenced from severe job and cost cuts at the company.

One anonymous insider told Ars that it was surprising to see a "for sale" sign being pinned to the MIPS wing, however, given that a decent strategy had been implemented for that part of the business following Imagination's restructure.

Arguably, though, the MIPS division is now in good shape to be sold, allowing Imagination to focus on an uncertain future if formal talks with Apple fail.