On this day in 1981, the IBM 5150, better known to the world simply as the IBM PC, had its debut. The 5150 actually wasn’t the first PC, or even the first IBM PC—the company had marketed the $20,000 5100, its first desktop computer, six years earlier—and its specs wouldn’t have impressed even the Geico cavemen. For $1,565, purchasers got a machine equipped with an Intel 8088 processor running at a 4.77 MHz and a luxurious 16 kilobytes of memory. (For you youngsters who are wondering what a kilobyte is, we’ll explain that some other time). It ran on a primitive operating system called IBM Basic, which was stored on either an analog audio cassette tape or a floppy disk (Anthony Michael Hall won a dozen of the latter for obtaining Molly Ringwald’s undergarments in “16 Candles,” but we digress). Nevertheless, it was a revolutionary advance. IBM was in a hurry to create an affordable computer for the mass market, so its design team chose to build it from off-the-shelf components produced by other manufacturers, rather than IBM proprietary parts. It also chose to use an open architecture—providing detailed specifications to anybody who cared to peruse them—and made the machine compatible with other manufacturers’ monitors and printers. As a result, other companies quickly reverse-engineered the 5150’s BIOs and began churning out low cost “IBM compatible” clones, loaded with the then-new operating system MS-DOS. Before long, every 12-year-old geek in America was begging his parents for one, and a new wired age had dawned. While you’re fully appreciating that, here are the science stories of the day.