Recommend multi-tasking OS/environment/DOS extender

[Nable]

Oh. May be somebody could recommend me some OS/environment/DOS extender that allows to run multiple 16bit DOS applications in a time sharing manner + some IO protection, e.g. the first application has direct access to primary IDE controller, 2nd - to secondary and 3d - to sata and the memory of all this apps don't share memory. I'll agree to manually assign ports but may be i don't need to write such OS from scratch. Please, don't mention MS Windows. ReactOS may be suitable, although i'm not sure that it's good in passthroughing real hardware to DOS guests.