Upgrading from MS-DOS through Windows 7
TheRasteri · Demo · 10 min · 2011 · YouTube title: Chain of Fools : Upgrading through every version of windows (HQ)
Why it's here
HN cites it as evidence of Microsoft's backward compatibility and of upgrade engineering done well.
What it covers
TheRasteri installs MS-DOS and Windows 1.0, then upgrades in place through nearly every Windows version up to Windows 7, checking which programs survive. Even Doom from 1993 still runs at the end.