But those giants of the 1970s fell victim to what's now widely called disruptive innovation, a concept popularized by the late Harvard professor Clayton Christensen. It's what happens when a product starts out at the bottom of an existing marketplace and eventually moves up in value to replace the established competitors.

The makers of supercomputers and mainframes, even IBM, were originally dismissive when a then-small maker of memory chips called Intel Corp. built a "computer-on-a-chip" for a Japanese adding-machine company.