Andrew's OS Lab: I've released a virtual museum with nearly every OS you can think of... (opens in new tab)

Nearly all well-known OSes and platforms (and many obscure ones) are included in some form, spanning the entire history of stored-program computing from the 1948 Manchester Baby to the present day. This is the result of over 20 years of collecting emulators and VM images; over 1700 VM installations are included, across over 250 platforms, representing nearly 600 distinct OSes.