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Micro House PC Hardware Library Volume II: Network Interface Cards And Modems Micro House PC Hardware Library Volume II: Network Interface Cards And Modems
by Micro House International, Inc. and Scott Mueller
Que, Macmillan Computer Publishing
ISBN: 078971664x   Pub Date: 06/17/98
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Resolving Conflicts Manually

Unfortunately, the only way to resolve conflicts manually is to take the cover off your system and start changing switches or jumper settings on your adapter cards. Each of these changes then must be accompanied by a system reboot, which implies that they take a great deal of time. This situation brings us to the first rule of resolving conflicts: When you set about ridding your system of resource conflicts, make sure that you allow a good deal of uninterrupted time.

Also make sure that you write down your current system settings before you start making changes. That way, you will know where you began and can go back to the original configuration (if necessary).

Now you are ready to begin your detective work. As you try various switch settings and jumper positions, keep the following questions in mind; the answers will help you narrow down the conflict areas:

  When did the conflict first become apparent? If the conflict occurred after you installed a new adapter card, that new card probably is causing the conflict. If the conflict occurred after you started using new software, chances are good that the software uses a device that is taxing your system’s resources in a new way.
  Are there two similar devices in your system that do not work? For example, if your modem and mouse—devices that use a COM port—do not work, chances are good that these devices are conflicting with each other.
  Have other people had the same problem, and if so, how did they resolve it? Public forums— such as those on CompuServe, Internet newsgroups, and America Online—are great places to find other users who may be able to help you solve the conflict.

Whenever you make changes in your system, reboot and see whether the problem persists. When you believe that you have solved the problem, make sure that you test all your software. Fixing one problem often seems to causes another to crop up. The only way to make sure that all problems are resolved is to test everything in your system.

As you attempt to resolve your resource conflicts, you should work with and update a system-configuration template, as discussed in the following section.

Using a System-Configuration Template

A system-configuration template is helpful, simply because it is easier to remember something that is written down than it is to keep it in your head. To create a configuration template, all you need to do is start writing down what resources are used by which parts of your system. Then, when you need to make a change or add an adapter, you can quickly determine where conflicts may arise.

I like to use a worksheet split into three main areas—one for interrupts, another for DMA channels, and a middle area for devices that do not use interrupts. Each section lists the IRQ or DMA channel on the left and the I/O port device range on the right. This way, you get the clearest picture of what resources are used and which ones are available in a given system.

This type of configuration sheet is resource-based instead of component-based. Each row in the template represents a different resource, and lists the component using the resource as well as the resources used.

To fill out this type of chart, you would perform the following steps:

1.  Enter the default resources used by standard components, such as serial and parallel ports, disk controllers, and video.
2.  Enter the default resources used by additional add-on components such as sound cards, SCSI cards, network cards, proprietary cards, and so on.
3.  Change any configuration items that are in conflict. Try to leave built-in devices at their default settings, as well as sound cards. Other installed adapters may have their settings changed, but be sure to document the changes.

Of course a template like this is best used when first installing components, not after. Once you have it completely filled out to match your system, you can label it and keep it with the system. When you add any more devices, the template will be your guide as to how any new devices should be configured.


Tip:  
Do not rely too much on software diagnostics such as MSD.EXE that claim to be able to show hardware settings like IRQ and I/O port settings. While they can be helpful in certain situations, they are often wrong with respect to at least some of the information they are displaying about your system. One or two items shown incorrectly can be very troublesome if you believe the incorrect information and configure your system based on it!

Unless your system fully supports PnP, then there is simply no standard way for software to determine resource usage in a PC system. In a non-PnP system, these programs will instead guess at how things are configured, and display these guesses with confidence, even though they may be incorrect.


Plug and Play Systems

Plug and Play (PnP) represents a major revolution in recent interface technology. PnP first came on the market in 1995, and most new systems come ready to take advantage of it. In the past, PC users have been forced to muddle through a nightmare of dip switches and jumpers every time they wanted to add new devices to their systems. The results, all too often, were system resource conflicts and non-functioning cards.

PnP is not an entirely new concept. It was a key design feature of MCA and EISA interfaces, but the limited appeal of MCA and EISA meant that they never became industry standards. Therefore, mainstream PC users still worry about I/O addresses, DMA channels, and IRQ settings. But now that PnP specifications are available for ISA-, PCI-, SCSI-, IDE-, and PCMCIA-based systems, worry-free hardware setup is within the grasp of all new computer buyers.

Of course, PnP may well be within your grasp, but that does not necessarily mean you are ready to take advantage of it. For PnP to work, the following components are required:

  PnP hardware
  PnP BIOS
  PnP operating system (optional)

Each of these components needs to be PnP-compatible, meaning that it complies with the PnP specifications.


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