(That reminds me: does anyone know whether automatic teller machines are PCs inside?)
I should know our cash machine line by now, but anyway... I think ours are basically PCs with OS/2 operating systems; having real multitasking is useful in a communication device, and it's a reasonably flexible environment for adding drivers for miscellaneous peripherals, like cash dispensers. A few years ago I saw a cash machine that was not working, and had a very dos-llike boot error message on the screen. Grocery store aisle signs are often driven by Amigas, and occcasionally have confused-Amiga messages on them. ObCrypto: according to someone on the net, some appallingly large fraction of teller machines don't use encryption on their comm links. (Grocery store signs do just fine without crypto :-), though some of the new radio-transmission shelf price labels might be interesting hacking for somebody with lots of time on their hands.)