Mail Archives: opendos/1997/05/14/20:48:30
> > Even though a DOS 16bit program doesn't have scheduling to worry about,
> > it still only runs at half the speed of a 32bit program; under NT and Win95
> > you can also set the priority of a program to 'real-time' which pretty much
> > takes over the operating system completely.
> 32 bit isn't double the speed of a 16 bit program! The *main* advantage
> that you can access larger areas of memory at once. For example, you can
> use a linear frame buffer, instead of using 4 segments and bank switching
> to access the video card. This is a *bit* faster since you don't have to
> bank switch, not because of using 32-bit instructions. Of course, using
> 32-bit instruction will help a bit too. Under NT, an ordinary user cannot
> set a priority to real-time BTW.
Ok, first off, if 32 bit isn't that much of an increase, why aren't we all
still using 16 bit? :) I just don't think there is any argument between the
advantages/speed etc of 32bit and 16 bit... As for NT, a program run by a
normal user (not the administrator) can update its priority to real time;
it uses a hack though... Its basically a program dependent thing which I
have seen running, I just have no idea how to do it... :) (Basically, the
game sets itself to real-time priority, and then sets itself back to normal
priority if alt-tab/alt-enter etc is hit)
> > > There's a Quake version for S3 ViRGE chipsets, this is what you should
> > > compare a WinQuake using DirectX 3.0 drivers, on the same system (using a
> > > ViRGE video card, of course!).
> > Are you talking about 3D acceleration in hardware? I Don't have that yet... :)
> > I am talking sheer CPU power...
> The only two advantages of DirectX is that it gives any program access to
> all the features of hardware acceleration (which is interesting) and
> overcome the GDI, which is a GUI-only concern, since there's no GDI to
> overcome in DOS.
Wouldn't it be great though if OpenDOS had access to all the features of
hardware acceleration? I have written tests to check on the speed of DirectX
blits from a backbuffer and software blits under DOS (even using the FPU
load/store method) and windows still outperformed DOS... Now if I could use
the hardware acceleration of my card in DOS, I'm sure it would outperform
the windows stuff, but remember, a 640x480x32 framebuffer is 1,228,800 bytes;
at 30FPS thats 36Mb to transfer - if you have hardware accleration moving
that around for you, thats a lot of spare time for the CPU - more than the
overhead of scheduling and task switching (if the game is the only thing
running)
Leathal.
- Raw text -