Chapter 9 Introduction to the Server
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ACPI Component
Architecture
(ACPICA)
an extension to the
original ACPI stan-
dard that provides
a non-proprietary
software package
for hardware
confi guration.
interrupt request
(IRQ)
a circuit that commu-
nicates with the CPU.
ACPI Component Architecture (ACPICA) is an extension to the original ACPI
standard. The goal of ACPICA is to create a non-proprietary software package
for confi guring hardware. An ACPICA-compliant device is operating system
independent. ACPICA is written in the C language and is an open standard
allowing any computer software or hardware manufacturer to share power-saving
features rather than developing proprietary power-saving features. ACPICA is
compatible with both 32-bit and 64-bit systems.
Some of the companies that participate with the goals of ACPICA are
Microsoft, HP, Intel, and several Linux organizations. To learn more about
ACPICA, check out the ACPICA Web site (www.acpica.org).
System Resources
System resources refer to resources such as interrupt requests, Direct Memory
Access channels, Input/Output ports, and memory. System resources are assigned
to components installed in the computer system such as hard disk drives, keyboards,
and mice. In a Windows-based server, you can view system resource assignments
in Device Manager.
Not all devices have all four types of resources assigned to them. For example,
some devices do not require a DMA channel assignment. System resources
typically cannot be shared between two devices. Sharing the same system resource
causes a system resource confl ict, referred to simply as a confl ict. Confl icts must
be resolved before the system can operate properly. An exception to this rule is
motherboard chips used to bridge different bus systems. A motherboard chip can
share an IRQ with a hardware device.
Interrupt Request (IRQ)
An interrupt request (IRQ) is a circuit that communicates with the CPU.
Hardware devices send an electrical signal to the CPU using an assigned IRQ circuit.
There are 16 IRQ assignments numbered from 0 to 15, Figure 9-14. Many of the
assignments cannot be changed, but some can. When Plug and Play devices are used,
the IRQ is automatically assigned. Typically, each hardware device must use a separate
Figure 9-13.
Power options for
a wireless network
adapter.