What IBM product did you use first?
My first experience with IBM was selling Tandy 1000 machines. The line I used most often to sell those computers was telling people that they were 100% compatible with IBM software. Then about 1998, a friend tried buying his first laptop off of eBay. It was a Think pad, and ran Windows 3.1 with AOL. Seems my brother had an IBM calculator for school in the early-70's, but that is a an old memory and may not be accurate. But, the "Tandy 1000, 64K memory, and completely compatible with any of IBM's software".