Given that the demo targets AT-class hardware, it is unlikely that something like PCem or MESS was used, because in those cases you'd actually have to select an

Given that the demo targets AT-class hardware, it is unlikely that something like PCem or MESS was used, because in those cases you'd actually have to select an AT-configuration to make it work, instead of an XT-configuration. DOSBox does not have this option, it always emulates AT-class hardware, in which case this demo 'just works'.