Toshiba SATELLITE 2455 - Manuel (Page 230)

230 If Something Goes Wrong
Resolving a hardware conflict
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you add each device, test it to make sure it and all previously
connected devices work.
The device most recently connected to the system is the one
most likely to be causing a hardware conflict.
Resolving hardware conflicts on your own
Computer components need resources to accomplish a task.
A device, such as a disk drive or a modem, needs a channel to
the computer’s Central Processing Unit (CPU). It also needs
a direct channel to the computer’s memory to store
information as it works. These channels of communication
are commonly referred to as system resources.
Interrupt Request Channel
The channel to the CPU is called an Interrupt Request (IRQ)
because it interrupts what the processor is doing and requests
some of the processor’s time.
NOTE: Some of the IRQs may be shared by multiple devices. This
is called IRQ sharing and is normal.
Direct Memory Access
Similarly, the data required by the device is stored in a
specific place or address in memory called the Direct
Memory Access (DMA). The DMA provides a dedicated
channel for adapter cards to bypass the microprocessor and
access memory directly. If two or more devices use the same
DMA, the data required by one device overwrites the data
required by the other, causing a hardware conflict.
Plug and Play
With Plug and Play and the Windows
®
XP operating system,
avoiding hardware conflicts is easy. Plug and Play is a