Flight Simulator was originally written by Bruce Atwick and was published by a company called subLogic. I believe that they were responsible for versions 1 and 2 before they sold the product to Microsoft. The original versions were very smooth, even on my crappy computer for the time. I found it very realistic (I have my pilot's licence so I'm a pretty good judge), but once Microsoft took over, I found that the realism decreased and the software required a top of the line games machine to run with any smoothness whatsoever.