AS400
This story reminds me of my very first "IT job". Written in quotes as I was actually a trainee engineer at the time. What was interesting was that after a year of writing reports on the AS400 I made the discovery that I actually knew more about the data structure of the system than the IT guys did. Probably not that surprising given my day to day job was pretty much data analysis by that point. Did discover that myself and the guy who I'd previously been asking for help on the reports had very similar tastes in TV shows (the Mark Dacascos series of The Crow was out at the time)