Redbox, a video rental service that operates out of an iconic red vending machine. I was not familiar with them (the last time I rented a video, it was on Betamax tape :), so I had to do a little research when reader Celeste S. emailed me the photo below, just to figure out what the heck she was showing me!
Celeste apparently happened by a Redbox that was opened (for servicing, I presume), and she snapped this photo. The vertical cylindrical unit is basically a big storage carousel that can spin around under the control of a computer. Each of the seven levels appears to hold about 60 DVDs, so the total capacity is around 420 DVDs. The “picker” on the right just moves up and down, between levels. The Redbox's computer can load or unload any slot by moving the picker to the right level and spinning the cylinder around to put the right slot in front of the picker.
Celeste took the picture so she could show her (homeschooled!) kids how a Redbox actually works. There are quite a few explanations available on the web, I discovered – along with some incorrect information and some speculation that dwarf trolls live inside of every Redbox :)
When I first saw Celeste's photo, it reminded me of machines I worked with almost twenty years ago: robotic tape libraries. These were quite popular at big companies in the '90s (and still around today, though less common). Some of the tape libraries could hold thousands of tapes; others just a few dozen. The cylindrical design – very much like the Redbox machine – was very common for the smaller tape libraries. That design allows a simple mechanism to get at a reasonably large number of tapes (the tapes, by the way, were considerably larger than a DVD!). Larger tape libraries tended to use a linear design, reminiscent of large libraries; they could generally be extended to be as large as you'd like them to be...