Datasheet

WHAT ARE THE FEATURES OF WINDOWS VISTA ARCHITECTURE?
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Local Procedure Call Facility
Local Procedure Call facility acts as a negotiator between user mode and kernel mode. From an
internal standpoint, Vista uses a client-server model to administer itself. Just as Vista connects to a
server and requests services from it, the Vista user mode requests services from the Vista kernel
mode. Those requests are handled by local procedure calls. Local procedure calls are also used in
standard client-server networks.
Virtual Memory Manager
Virtual Memory Manager oversees how Vista uses virtual memory. To increase the amount of
usable memory space, Vista uses hard-disk space as memory when it runs out of memory (which
can happen fairly quickly with some high-powered programs). The disk memory is known as vir-
tual memory.
Win32K and GDI
The Win32K and Graphics Device Interface (GDI) are the graphics subsystem of Vista. The graphics
functions in earlier versions of Windows NT were provided by the Win32 subsystem in user mode.
Microsoft moved the graphics subsystem into Executive Services for version 4 to give the graphics
functions a performance boost. In fact, this resulted in the single greatest increase in the apparent
speed of Windows NT 4.
User Mode
In the Vista user mode, each of your programs runs in a separate memory space, an arrangement
that protects each program from the others in case one should crash. This is true for 64-bit, 32-bit,
and 16-bit programs, both Windows and DOS.
NOTE The 64-bit version of Vista is far more restrictive about what it will run than the 32-bit ver-
sion. While the 32-bit version will run 16-bit libraries, the 64-bit version won't. Consequently,
you'll find that many of your older applications won't work with the 64-bit version of Vista. This
limitation isn't due to Vista, but in the way that the 64-bit environment must work to provide the
benefits that it does.
The user mode is divided into subsystems. Each subsystem handles a different type of applica-
tion and can report directly to the kernel mode. The subsystems are described briefly in Table 1.1.
In addition to the subsystems noted in Table 1.1, user mode may also contain VDMs (video dis-
play metafiles). A VDM simulates a computer running MS-DOS 5, with 16 MB of RAM and con-
ventional, expanded, and extended memory. As stated earlier in this chapter, this simulation
makes it possible to run MS-DOS programs on Vista. It also enables you to run 16-bit Windows
applications by simulating Windows 3.1 running on that MS-DOS computer with 16 MB of mem-
ory. By default, Vista starts all 16-bit Windows applications in the same Win16 on Win32 or WOW
environment. This simulates exactly the environment the programs were written to operate in
under Windows 3.1. However, Vista gives you the ability to start the application in a separate mem-
ory space, which creates another WOW for each 16-bit Windows application.
Remember that the WOW environment imitates Windows 3.1 so well that it even hangs just
like the old Windows did! That means that if one of your 16-bit Windows applications crashes,
it will take all the other 16-bit applications with it—unless you have chosen to start them in
their own memory spaces, in which case the other 16-bit programs will keep running without
a problem.
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