Shares in Imagination Technologies plummeted on the news that Apple would stop using its GPU (graphical processing unit) IP and turn to fully in-house designs for future iDevices. Apple, which is a shareholder in Imagination, has used the UK firm’s GPU designs in its mobile chips since the first iPhone, and incorporates them in its Ax system-on-chip platforms. But the smaller company announced this week that Apple has given notice that it will terminate the current deal in 15-24 months’ time, because it has started working on an entirely inhouse design. Imagination was defiant, saying in its statement: “Apple has not presented any evidence to substantiate its assertion that it will no longer require Imagination’s technology, without violating Imagination’s patents,…