When you think about it, any wristwatch which does something useful beyond telling you the time of day arguably qualifies as a smartwatch. By that standard, the concept has existed for more than a century–ever since the first chronographs added a handy stopwatch to their timekeeping capabilities.
But watch-sized devices really got versatile in the 1970s and 1980s, when miniaturized electronics made it plausible to shrink down gadgets of all sorts into something you could strap to your person. Radio, TV, video games, paging, and even personal computing all got wearable, in devices which often attracted plenty of attention in magazines such as Popular Mechanics and Popular Science.
For all the attention they got, most of these devices didn’t sell in vast quantities. Many were commercial failures by any definition. The moral of some of the devices you’re about to get acquainted with is, basically, that just because you can build something into a watch doesn’t mean that you should do so. That’s one which the smartwatch makers of 2014 and beyond would be smart to heed.