I can remember playing around with VGA commands that worked just like BIOS calls. You set certain registers and made called the service routine to set the VGA mode and stuff. Then you would write into the video memory to create lines and circles and other shapes. And thousands of hours later and a million lines of code later I might have had something worthy of a game engine. I did manage to make a one level crappy PACMAN that ate up the energy pills and that was about it because I didn't make any of the munchy bad guys to chase him around and make an actual game of it. Anyway, bite the bullet, and learn either OpenGL or DirectX. Don't mess around with DOS, I don't even know if DOS GFX api's would work under XP or Vista. And why take your 64 or 128 or 256 Meg super high res video card with 256 bit bandwidth and turn it into a crappy retarded VGA card? There are lots of downloadable books on OpenGL and DirectX. There is even one for VB .NET (and others using C#) using managed DirectX. I'd start there.
If you are into C++ you might try using WildMagic, a heavy duty and free game/modelling engine with 3d collision handling, a physics engine, advanced linear algebra and ODE solver routines and tons more. You could not write this stuff in 10 years, even if you had PhDs in math and physics. And there are a few books written for it that you can download. If I was into graphics that is probably where I would go.