Let's do the time warp again! (danananananana) Anyway. You need to use XMS or EMS or some other DOS memory extender if you want to go beyond 640K. Thankfully (for me, not you) I never did any heavy duty DOS programming. Even staying within the lower 640K was a nightmare I don't ever want to repeat. So unless there are fancier tools available now, do some googling on expanded or extended memory. DOS/4GW was one too, I think? Several games used that IIRC.