[ The PC Guide | Systems and Components Reference Guide | Motherboard and System Devices | System
Resources | System Configuration ]
Assigning Resources to Devices
Many devices have fixed resource assignments that cannot be changed. Most system
devices are like this. In addition, it is generally best not to change (or try to change)
the resource settings for standard devices like IDE hard disk controllers unless you both
really know what you are doing and there is a compelling reason to change them. The
following devices usually have hard-coded resource settings that cannot be changed: system
devices, keyboard, PS/2 mouse, floppy disk controller, primary IDE controller, video card.
Others can generally be changed, although it makes more sense for some devices than for
There are several different ways that are generally used to set or change resource
settings for devices:
- Hardware Settings: Resource assignments on some cards, especially older ones, is
done by hardware on the device itself. This involves changing the settings of jumpers and
switches, usually on the circuit board of the device, to tell it what resources to use.
This is similar to the way most motherboards are
configured. Hardware configuration has the great disadvantage of being a pain if you
ever want to change the resources: you have to open the box and usually pull out the card
to get to the jumpers. It has one great advantage however: certainty. You always know that
if you put the jumper on say IRQ7, the card will try to use IRQ7 (if it isn't busted of
course. :^) ) You can always open the box and look at the card and get visual confirmation
of how it is set up. You cannot do this with software-based configuration.
- Software Configuration Programs: Many newer cards are configured using special
software config programs that come with them. You run the program and select the resources
you want to use, and the program writes the information into a special rewriteable EEPROM
placed on the device for that purpose. This is similar to the way a flash BIOS is used to upgrade the system BIOS using
software, on a smaller scale.
Devices that use configuration programs like these are much more convenient than those
that use hardware settings, because you can change the resources without opening the box.
However, they have the disadvantage of being dependent on the configuration program; if
you lose the disk you'll need to get another copy of the program to change the settings.
You also can't tell what the settings are with the power off, and you run the slight risk
of scrambling the card's settings if you say, lose power while it writes new settings to
- Plug and Play: Newer devices that subscribe to the Plug and
Play standards can be automatically configured under certain conditions when used in a
machine that supports Plug and Play, with an operating system that supports it. Plug and
Play is an attempt to eliminate the large amount of work in assigning resources to devices
and resolving conflicts. When it works properly, resources are dynamically and
automatically assigned and reassigned and you don't have to worry about making everything
In addition, the use of a PnP operating system like Windows 95 will normally allow you to
change device resource settings using the built-in Device Manager, giving you override
control if you don't like what PnP chose for your device, and eliminating the need for
special configuration utilities. However, often problems result from the system making
poor resource choices or having difficulties dealing with devices in the system that are
not themselves PnP-compatible.
Tip: It is always a good
idea, once you have your system configured in a way that makes sense and works for you, to
record the system configuration for future reference.
Next: Problems With Changing Default Resource Assignments
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