Behind-the-Scenes Changes
To make the new operating system more reliable and perform better, Microsoft has rewritten large portions
of Vista’s code base2 MAMAMAXIMXIMXIMXIMUUUUMMPPPCC JUNE 2006
The new permission system permeates all of Vista. It will let
you prevent your kids from playing inappropriate games.New Graphics Technology
You already know all about Aero Glass, but we haven’t really talk-
ed about the enhancements to the base levels of the operating
system that make the vector-based Aero UI work. To make the 3D
desktop feasible, Microsoft ditched the ancient 2D-only GDI and
replaced it with the totally redesigned Windows Desktop Driver
Model (WDDM). Microsoft based Vista’s new display driver model
on DirectX 9, with some serious updates to both improve stability
and work effectively with multiple target windows.
Vista’s new graphics-driver model allows the OS to dis-
tribute GPU cycles, much like it apportions CPU cycles. This
GPU virtualization lets multiple applications access the 3D
functionality of the GPU at the same time. In Windows XP theGPU is an all-or-nothing resource; when you run a 3D app in a
window, you experience greatly reduced performance because
the GPU has to keep switching from 2D to 3D mode. In Vista,
those state-changes are no more, and windowed performance
of 3D apps is greatly improved.
WDDM also improves stability and error recovery. In XP, when
an app crashes the graphics driver, it usually means you’ve got to
reboot the PC. Vista’s graphics-driver model lets the OS reinitial-
ize the graphics card on the fl y in the event of a crash. After a few
weeks with Vista, we can attest to the fact that the OS is actually
pretty good at recovering when beta drivers crash.DirectX 10
In addition to the WDDM enhancements, there’s also a whole
new version of DirectX in Vista. DirectX 10 adds a completely
new type of shader—the geometry shader—as well as a com-
plete unifi cation of the different shader-model languages. The
geometry shader will allow developers to modify basic struc-
tures. Unlike the vertex shader units, which programmatically
modify single vertices, the geometry shader will work on entire
primitives—such as fl owing cloth and sheets of water.Permissions Revamp
One of Microsoft’s main goals for Vista was to accommodate
a new security model. In Vista, everyone—even people who
would typically use an Admin account in XP—use an account
that doesn’t have permission to install apps in Program Files.
It seems like a fairly simple change, but there’s a lot more to it
than you might think.
Much like a Linux install, Vista only allows you to run appli-
cations from folders with the appropriate permissions. And it
locks down the write permissions on those folders so that mal-
ware can’t use your Administrator permissions to install itself to
a hidden folder on your drive and then run whenever it wants.
On a properly confi gured Vista machine, you’ll have to explicitly
give permission whenever any application tries to put anything
in Program Files. Bravo.
But what about all those legacy applications that need write
access to the Program Files directory? All those games that
save your game in the Program Files directory will continue to
work. Vista has a contingency: You’ll install your legacy app in
C:/Program Files, just like always, but any fi les that the app tries
to write to its C:/Program Files sub-directory will actually end up in
a sub-directory of your user profi le. Any fi les in that directory willappear to the application to be in the correct place, so the app
will work, but your main Windows install will be secure.
The upshot is this: Even if you manage to infect a properly
confi gured Vista machine with spyware, viruses, or some other
Internet nasty, the infestation will be contained within your user
profi le. In a worst case scenario, you should be able to back up
your important data, create a new account, and delete your old
one to fi x any problem.Vista Preview
Continued on page 30 ËContinued from page 26