As I said, I started with BK for DOS in 1990 which came on HD 3.5" floppies. Don't know which version # it had. Over the years, Mr. Steed upgraded BK to a Windows version and kept enhancing it to 5.2G before starting on BK6.
Still, 5.2 is basically a DOS/Win 3.1 prog underneath which is why it doesn't run on 64-bit Windows -- which doesn't support the DOS command prompt window either which I use every day.