The iPhone of slide rules

I have vague memories of my older scientist brother Mark wearing a slide rule in a leather case on his belt. It was really one of the first wearable computers, although a mechanical, analog one. Then in 1974, he was able to purchase a Texas Instruments SR-50, the first mass-market commercial electronic calculator. The slide rule was buried in Mark's desk drawer, where the SR-50, and later his Sharp Wizard, Palm Pilot, and their descendants would ultimately end up as well. (He died wearing a calculator wristwatch!)

In this episode of Numberphile, Alex Bellos explains the seduction of the slide rule and also the Halden Calculex, a device he calls the "iPhone of Slide Rules."