User's Manual

182
If Something Goes Wrong
Resolving a hardware conflict
5.375 x 8.375 ver 2.4.0
A plan of action
The smooth operation of the system depends on the
interaction of all devices, programs, and features. If the
system or one of its attached devices isn’t working, resolving
the problem can be time-consuming and frustrating.
The recommended procedure for getting multiple devices to
work together is to add and set up one device at a time. After
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. If two or more devices use the
same IRQ, the processor does not know which device is
asking for attention. This causes a hardware conflict.
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.