20 years of Windows Upgrades

The priority of backwards-compatibility in the Microsoft development culture is sometimes overlooked. Check out this video of upgrading a single machine from DOS/Win 1.x through each successive version of Windows up to Windows 7. You can still run many (most?) 20-year old DOS and Win 1 apps on Windows 7. http://www.networkworld.com/community/blog/absolutely-brilliant-windows-upgrades-through