Someday, computers will only be the size of a football field.

Hercules! Not the shiny muscle man from the past, but a handy emulator for IBM S/360, S/370, S/390, and z/Arch mainframes. Unfortunately, because of IBM’s bullheadedness, you can only run operating systems released when the world was young, unless, for whatever reason, you decide to run something released after the Reagan Administration.
You can learn how easy you young whippersnappers have it now, but beware: to effectively use most of these systems, you will need to descend into Hell.