Wujec, a "practitioner of business visualization," looks at how the astrolabe was the must-have device of the 13th century. From the article:
How would you tell the time, say, 600 years ago? How would you do it? Well, the way you would do it is by using a device that's called an astrolabe. So, an astrolabe is relatively unknown in today's world. But, at the time, in the 13th century, it was the gadget of the day. It was the world's first popular computer.