New York - Motorola Inc. says it has developed a computer chip that runs 35 times faster than today’s models, an innovation it hopes will lead to faster, smaller and cheaper cell phones, computers and other telecommunication equipment.While praising the company’s innovative solution, scientists were cautious about predicting how soon devices based on the technology might reach the market.Motorola says it has solved a 30-year-old challenge: creating a semiconductor that combines the durability and economy of silicon with the high speed of crystal compounds used in lasers and fiber optic equipment.Its scientists did so by layering gallium arsenide, a fast but brittle semiconductor, onto silicon by way of a spongy middle, which binds the two pieces.“It’s a monumental change in the constraints on the construction of semiconductor systems,” said Dennis Roberson, chief technology officer of Motorola. “We’ve opened the door on a whole new world.”