Interesting article from Fast Company about the Hewlett-Packard 12c. The device debuted in the early 80s and has barely evolved for more than 25 years:

So what to make of the Hewlett-Packard 12c, essentially unchanged since its 1981 debut and, 15 million units later, still one of the company’s top-selling calculators? Everything it does can be replicated–in some cases, with far greater ease–on an Excel spreadsheet. Yet after 25 years, the 12c remains a tool of choice among finance and real estate professionals worldwide. It is still, as one junior analyst put it, “part of the banker’s kit”–an unquestioned marker of credibility, if not good breeding.