“But this is not another rant against email. Email is magic. It enables abundant, free communication. Consider how far we have come in less than a century: In 1915 — the year my grandfather was born — Alexander Graham Bell picked up a telephone in New York and made the country’s first transcontinental call to San Francisco. Adjusting for inflation, the price of a 3-minute call back then was $440. Today, I video chat through my Gmail account with friends in Budapest or Tokyo — for free. Seriously, magic.” Tech Fortune Four basic periods Characterized by a principal technology used to solve the input, processing, output and communication problemsof the…