Hardware Reference
In-Depth Information
Note
Although 32-bit versions of Windows can support up to 4GB of RAM, applications cannot
access more than about 3.25GB of RAM. The remainder of the address space is used by
video cards, the system ROM, integrated PCI devices, PCI cards, and APICs.
64-bit Windows runs 32-bit Windows applications with no problems, but it does not run
16-bit Windows, DOS applications, or any other programs that run in virtual real mode.
Drivers are another big problem. 32-bit processes cannot load 64-bit dynamic link librar-
ies(DLLs),and64-bitprocessescannotload32-bitDLLs.Thisessentiallymeansthat,for
allthedevicesyouhaveconnectedtoyoursystem,youneedboth32-bitand64-bitdrivers
for them to work. Acquiring 64-bit drivers for older devices or devices that are no longer
supported can be difficult or impossible. Before installing a 64-bit version of Windows,
be sure to check with the vendors of your internal and add-on hardware for 64-bit drivers.
Tip
If you cannot find 64-bit drivers designed for Windows Vista or Windows 7, look for 64-bit
drivers for Windows XP x64 edition. These drivers often work very well with later 64-bit
versions of Windows.
Although vendors have ramped up their development of 64-bit software and drivers, you
should still keep all the memory size, software, and driver issues in mind when consid-
ering the transition from 32-bit to 64-bit technology. The transition from 32-bit hardware
to mainstream 32-bit computing took 16 years. The first 64-bit PC processor was released
in 2003, and 64-bit computing really didn't become mainstream until the release of Win-
dows 7 in late 2009.
Processor Benchmarks
People love to know how fast (or slow) their computers are. We have always been inter-
ested in speed; it is human nature. To help us with this quest, we can use various bench-
mark test programs to measure aspects of processor and system performance. Although
no single numerical measurement can completely describe the performance of a complex
device such as a processor or a complete PC, benchmarks can be useful tools for compar-
ing different components and systems.
However, the only truly accurate way to measure your system's performance is to test the
system using the actual software applications you use. Although you think you might be
testing one component of a system, often other parts of the system can have an effect. It
is inaccurate to compare systems with different processors, for example, if they also have
