Troubleshooting

Your PC has been working

fine for some time now. And you decide to add something

new–a CD-ROM driver or a sound card or maybe a new

display card. And suddenly your machine starts

misbehaving. What went wrong when you added a new card?

Surely you fixed the card properly and installed all the

drivers supplied with the card. Time for a panic call to

the vendor? Will they be able to help? Before reaching

for the telephone, here are a few things that you can do

yourself.

A majority of these

problems are caused by IRQ conflicts. PCI cards and Win

95 were supposed to make IRQ conflicts a thing of the

past. Unfortunately, not all your installed cards are

PCI, and even with PCI, we have come across rare

instances of clashes that had to be resolved manually.

The basic rule is that no

two devices can have the same IRQ. Some system devices

are provided with pre-defined IRQs. For example, COM

ports take IRQ 3 and 4, parallel port 7, disk controller

14 and 15, and sound card normally takes IRQ 5. But you

can change that. Other devices like Network and SCSI

cards for your scanner, or CD-Writer might prompt you for

manual configuration.

In case of ISA devices you

have to set the IRQ manually. PCI devices are

automatically set to available IRQ numbers by the BIOS

itself. Setting PCI configuration to Auto mode in the

BIOS will generally do this. If for any reason PCI

devices clash with automatic IRQ settings, you have to

change these settings manually. But before that you have

to take care about what you are actually changing.

In Win 95, you can easily

configure and clear IRQ conflicts from System Properties

control panel. From the Start button, select

Settings/Control Panel/System. Select Device Manager.

This tab lists all devices connected to your system.

If you have selected the

View devices by type option, you will see a list of

device types like hard drive, display adapter, floppy

disk controllers, etc, listed in alphabetic order.

Clicking on the + sign in the box on the left of any of

these items, displays a list of installed devices of that

type. For example, clicking on the + sign next to the

display adapters shows the installed display adapters

(normally there should be only one display adapter). Go

to the device that is not functioning and click on the +

sign to see what are the installed devices.

An item that is installed

but not present or not working is identified with a black

exclamation mark in a yellow circle. Select this item and

click on the Properties button at the bottom of the

System Properties window. The Resources tab lists the IRQ

being used. In order to change the IRQ, you need to first

put off the Use AutomaticSettings option and then click

on Change Setting after selecting the resource

whose value you want to change. Note that all devices may

not have resource allocations, and that all devices with

resource allocations may not allow you to change them

from here (you may need to set the BIOS first).

A more common occurrence

is that devices that are no longer installed on the

system still show up, or multiple instances of the same

device may be installed. In either case, the offending

instances can be deleted by selecting them and clicking

on Remove in the System Properties window.