[UltraSane]

If it uses any analog hardware it makes emulation much harder.

[M95D]

If it uses any digital hardware directly accessed by software (something that Win9x still allowed, see DOS games w/ ISA sound cards), it makes virtualization impossible.

[stavros]

Why is that? Doesn't virtualization virtualize the hardware? I'm not sure why virtualization is impossible there, as QEMU can run plenty of old DOS games.

[M95D]

Yes, but what use is a virtual radar, or a virtual radio?

[UltraSane]

No, pretending to behave like other digital hardware is exactly what virtualization does.