Toshiba Tecra 500CS User Manual page 315

000-book.bk : 15-trbl.fm5 Page 336 Thursday, May 16, 1996 2:07 PM
336
If Something Goes Wrong...
Resolving a Hardware Conflict
Resolving Hardware Conflicts on Your Own
Computer components need resources to accomplish a task. A
device, such as a CD-ROM 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 doesn't know which device is asking for atten-
tion. This causes a problem.
Direct Memory Address
Similarly, the data required by the device is stored in a specific
place or address in memory called the Direct Memory Address
(DMA). If two or more devices use the same DMA, the data
required by one device overwrites the data required by the other. If
either of these situations occur, you have a hardware conflict.
Plug and Play
With Plug and Play and Windows 95, avoiding hardware conflicts
is easy. Plug and Play is a computer standard that helps the system
BIOS (basic input/output system) and Windows 95 to automati-
cally assign system resources to Plug and Play-compliant devices.
In theory, if every device connected to the computer is Plug and
Play-compliant, no two devices will compete for the same system
resources. You simply plug in the device and turn your computer
on. Windows 95 automatically configures your system to accom-
modate the new device.
Part I: Getting To Know Your Computer