| Who's in control?
System resources can be allocated by either the BIOS
or by the operating system, or both.
Most modern BIOS are 'Plug and Play',
in other words, they recognize that the operating system
can look after all the hardware resources on it's own
and give you the option to do this.
Have a look at your BIOS settings when
you boot up the system. If there are options like the
two below, you have a Plug and Play BIOS.
PNP OS Installed - Yes/No
Resources Controlled By - Auto/Manual
If you do not have a Plug and Play BIOS
then you may need to set all of your device resources
in the BIOS rather than the operating system.
Caution! - Windows 2000 and Windows XP
(Home or Professional edition) handle resources very differently
to Windows 95,98,98SE & ME.
If your operating system is Windows 2000 or Windows XP
(Home or Professional) you should not use this guide.
An expanded guide will be available soon covering these
operating systems.
To BIOS or not to BIOS
In order to identify a conflict, you need to establish
how the hardware resources are being allocated in your
system.
Either the BIOS or the System Device
Manager in Windows can allocate the resources.
Non Plug and Play devices (All ISA
devices) are normally allocated resources by the BIOS
whereas Plug and Play devices (PCI
& AGP)are
normally allocated by the System Device Manager.
To find out if the BIOS in your system
is controlling the allocation of resources you need to
enter the BIOS Set Up program which can normally be accessed
when your computer is performing the POST
routine.
There is a section about the BIOS Set
Up routine in the Techrescue.net
guide to installing new hardware.
There are a number of different BIOS
types which I have covered below. Let
me know if you identify any others and I will include
them here.
BIOS Type 1
Some BIOS list IRQ's from 3 to 15 with one of the following
options set on each entry :-
Auto - this means the BIOS will decide
on the IRQ
allocation.
Legacy - Only 16bit ISA
cards can use the IRQ
PCI -Only PCI devices can use the IRQ
Both - Both an ISA or a PCI device can use the IRQ
Assuming you have BIOS type 1 :-
If the conflicting device is a PCI device on IRQ 11, then
IRQ 11 must be set to either 'Both', 'Auto' or 'PCI'.
If you want to make the PCI device use
a different IRQ you should set IRQ 11 to 'Legacy' or 'ISA
only'.
The BIOS should allocate a different
IRQ to the device after saving your changes and rebooting
the system.
Remember that there must be an IRQ available
for the device to move to when you make your change.
If you cannot find an IRQ to free up,
try disabling COM ports or USB controllers if you do not
use devices attached to these ports in your system.
These ports are allocated IRQ's by default and you can
free up the resources if you do not ave any devices attached
to them.
BIOS Type 2
Other types of BIOS list the specific
IRQ assigned to each slot on the motherboard i.e.
Slot 1 - IRQ 10
Slot 2 - IRQ 11
Slot 3 - IRQ 8
Slot 4 - IRQ 5 etc.
Identify which slot you are using for
the new device and change the IRQ that is listed for that
slot in the relevant BIOS menu e.g. Change Slot 2 - IRQ11
to Slot 2 - IRQ 9.
Remember you still need to have a spare
IRQ for the card to use (Try disabling COM ports or USB
ports if they are not needed - see BIOS Type 1)
BIOS Type 3
Many older BIOS do not allow resource control through
the BIOS.
If your BIOS falls into this category
you could try a BIOS upgrade.
These are normally available via your
motherboard manufacturers website (See
the Techrescue.net BIOS datasheet).
The only way to change the resource settings
in a BIOS of this kind is to remove the device, reboot
without it and then put it back in a different slot before
rebooting again. The BIOS should then detect the device
again and allocate a different IRQ. |
Resolving Hardware Conflicts