There is a much longer (and more detailed) description of the history of the transition from DOS to Windows: https://www.filfre.net/2018/06/doing-windows-part-1

There is a much longer (and more detailed) description of the history of the transition from DOS to Windows: https://www.filfre.net/2018/06/doing-windows-part-1-ms-dos-and-its-discontents/ https://www.filfre.net/2018/06/doing-windows-part-1-ms-dos-a... (That's part 1 out of 9) It has a slightly different focus: it doesn't mention PIF files, but spends time on the business relationship between IBM and MS. It also discusses OS/2.