Shares in Imagination Technologies plummeted on the news that Apple would stop using its GPU (graphical processing unit) IP and turn to fully inhouse 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,…