In the mid-eighties, I was working on some app that did serial port communications, probably under PC-DOS. The program was failing to communicate, and I spent

In the mid-eighties, I was working on some app that did serial port communications, probably under PC-DOS. The program was failing to communicate, and I spent most of a week stepping through the debugger, watching it send the characters down the cable, working perfectly. But it was failing at normal speed. It finally occurred to me that maybe the hardware wasn't quite working, so I ran a diagnostic and it immediately failed. It was probably a lightning surge from months before that made that port "special". The psychic scar of that week made such an impression on me that I bought a used 5KW 120lb ultra-isolation transformer for $75, and I have run all my various equipment behind it ever since. I've never had another hardware failure due to electrical surge, and my cat loves to sleep snuggled against it for warmth.