Lesson 3: Working with Device Drivers and NICs
In this lesson, we examine the role of network interface cards (NICs) and
how they are installed. Without a properly configured NIC, our computers
will be unable to talk to the physical media that we installed in Lesson
1. NICs were introduced and discussed in detail in Chapter 2 in Lesson
2: The Network Interface Card. It will help to review that lesson and
refamiliarize yourself with the concept of interrupts and the types of
NICs. Here, we carry that lesson a step farther, covering NIC installation
The Role of Drivers
A driver (sometimes called a device driver) is software that enables a
computer to work with a particular device. Drivers are also discussed in
the context of the OSI Reference Model in
5, "Introducing Network Standards."Although a device might be installed
on a computer, the computer's operating system cannot communicate with
the device until the driver for that device has been installed and configured.
It is the software driver that tells the computer how to work with the
device so that the device can perform its job.
There are drivers for nearly every type of computer device and peripheral
Usually, the computer's operating system works with the driver to make
the device perform. Printers provide a good illustration of how drivers
are used. Printers built by different manufacturers have different features
and functions. It is impossible for computer and operating-system manufacturers
to equip new computers with all the software required to identify and work
with every type of printer. Instead, printer manufacturers make drivers
available for each of their printers. Before your computer can send documents
to a printer, you must install, or load, the drivers for that printer so
that your computer will be able to communicate with it.
Input devices, such as mouse devices.
Hard and floppy disk drives and controllers.
Multimedia devices, such as microphones, cameras, and recorders.
Printers, plotters, and tape drives.
As a general rule, manufacturers of components, such as peripherals
or cards that must be physically installed, are responsible for supplying
the drivers for their equipment. For example, NIC manufacturers are responsible
for making drivers available for their cards. Drivers are usually included
on a disk that accompanies computer equipment when it is purchased. Drivers
can also be downloaded from a service such as The Microsoft Network (MSN),
CompuServe, or the manufacturer's Internet site or bulletin board.
The Network Environment
Network drivers provide communication between a NIC and the network redirector
running in the computer. (The redirector is part of the networking software
that accepts input/output (I/O) requests for remote files and then sends,
or redirects, them over the network to another computer. Redirectors are
introduced in Chapter 4, "Survey of Network
OperatingSystems.") The network administrator uses a utility program to
install the driver. During installation, the driver is placed on the computer's
Drivers and the OSI Reference Model
NIC drivers reside in the Media Access Control sublayer of the data-link
layer of the OSI Reference Model. The Media Access Control sublayer is
responsible for providing shared access for the computer's NICs to the
physical layer. In other words, the NIC drivers ensure direct communication
between the computer and the NIC. This, in turn, establishes a link between
the computer and the rest of the network. Figure 8.13 shows the relationship
of a NIC to the network software.
Figure 8.13 Communication between the NIC and network software
Drivers and Networking Software
It is common for the NIC manufacturer to provide drivers to the networking
software vendor so that the drivers can be included with the network operating
The operating system manufacturer's hardware compatibility list (HCL)
lists the drivers they have tested and included with the operating system.
Even if the driver for a particular card has not been included with the
network operating system, it is common for the NIC manufacturer to include
drivers for most popular network operating systems on a disk that is shipped
with the card. Before buying a card, however, you should make sure that
the card has a driver that will work with your particular network operating
If you are upgrading from one operating system to another (from
Microsoft Windows 95 to Windows NT, for example) you might need to contact
your NIC supplier and download a new driver. It is a good idea to do this
before you start the upgrade.
Working with Drivers
Working with drivers encompasses a variety of tasks, including installation,
configuring, updating, and removal.
Each network operating system has its own method for installing drivers.
Most popular network operating systems use interactive graphical interfaces,
or dialog boxes, that guide the installer through the process.
Microsoft Windows NT Server, for example, features a utility called
the Control Panel. This employs dialog boxes that lead the user through
the process of installing a NIC driver. Figure 8.14 shows several of the
dialog boxes that appear during the installation of a NIC network driver
on Windows NT.
Figure 8.14 Installing a NIC on Windows NT Server
Network interface cards usually have configurable options that must be
set correctly for the NIC to function properly. As discussed in Chapter
2, Lesson 2: The Network Interface Card, this
can be accomplished with jumpers or switches.
Most of the newer NICs are software-configurable or Plug and Play (PnP)
compliant. There are no DIP switches or jumpers to configure. The configuration
is accomplished through the software during or after the installation of
the drivers, or—as with a PnP-compliant system, such as Microsoft Windows
95 or Windows 98—the operating system attempts to configure the hardware
device automatically. While Windows NT 4.0 is currently not PnP-compliant,
it will attempt to recognize your devices. If the attempt is not successful,
you will be required to supply the drivers from a disk provided by the
manufacturer. If you already have that disk with the correct drivers, it
is often easier simply to tell Windows NT where to find them.
Occasionally, a manufacturer will write additions or changes to a driver
to improve a component's performance. Manufacturers can send these driver
changes by mail to registered users, post them on an Internet bulletin
board, or make them available through a service such as The Microsoft Network
(MSN), CompuServe, or the manufacturer's Internet site. The user can download
and then install the updated driver.
The process of updating drivers is similar to installing them, although
you might need to remove the old driver first. Be sure to look for any
readme files that come with the software. The readme files will inform
you of the correct procedure for installation. Some drivers, especially
those that have been downloaded from the Internet or a bulletin board,
are in the form of executable files. For these, double-click on the file
name, and the executable file will perform the installation.
It is sometimes necessary to remove drivers, such as when the original
driver conflicts with newer drivers. If a piece of equipment is being removed,
remove its drivers at the same time, too, to ensure that no conflicts arise
between the old drivers and any new drivers that are installed.
The process of removing a driver is similar to that of installing a
driver. Figure 8.15 shows the Adapters tab of the Network Window in a Windows
NT work session. In this window, you need only select the driver and then
click on the Remove button.
Figure 8.15 Removing a driver
Tackling a NIC installation can range from a routine, predictable chore
to a frustrating failure. The best way to minimize problems is to do a
little planning first. Expansion cards were covered in Chapter 2, in Lesson
2: The Network Interface Card. Before purchasing NICs, it's helpful
to keep several important points in mind.
Type of Expansion Slot
A NIC is one of several kinds of expansion card for a personal computer.
As we learned earlier, a computer can contain a variety of expansion bus
types. You might encounter ISA, EISA, Micro Channel, and/or PCI buses.
Whether you are purchasing a card for a single computer or cards for an
entire network, you need to know the answers to three questions for each
computer you plan to link:
What type of expansion bus does it have?
Does it have a slot available for the card?
Which type of cable will be connected to it?
Type of Card
Not all NICs are equal. In addition to being designed for installation
on different expansion buses, NICs are specified by network type. For example,
a card designed to work on an Ethernet system will not work on a Token
Ethernet can be configured in two speeds: 10BaseT (10 Mbps) or 100BaseTX
(100 Mbps). Many newer NICs can run at either speed, but older cards run
only at 10 Mbps. When designing your network, be sure to keep future networking
needs in mind. It might be more cost-effective to obtain dual-speed NICs
now than to have to purchase new cards later.
As we have seen, there is a variety of media from which to choose. Be sure
to look carefully at the cards you purchase to ensure that they will fit
the cabling of the network. Some cards have a selection of BNCs or RJ-45
connectors; some will have only one or the other.
Purchasing network cards with diagnostic lights built in can be a good
investment that will pay off later. The purpose of these lights is to indicate
the status of the card and the network. They can tell you if the card is
properly connected (it detects the presence of a network) and when data
is being processed through the card. As shown in Figure 8.16, some NICs
feature one, two, or three light-emitting diodes (LEDs) that are visible
on the outside of the computer. Typically, a green light indicates that
a proper connection exists between the card and the media. A flashing yellow
light usually indicates that the card is processing data.
Figure 8.16 Diagnostic lights
Installing a NIC
Installing a NIC is like installing any other expansion card. The following
is a summary of the procedure, step-by-step:
Read the documentation that comes with the card. Take note of any special
requirements or limitations before you begin the installation.
Determine which interrupt request numbers (IRQs) and I/O addresses are
available on the computer. This is especially true if you are installing
in an operating system that is not equipped with PnP technology. This can
usually be done with the system information software that accompanies the
computer's operating system.
Configure any jumpers or switches, if required. If no switches or jumpers
are on the card, use the installation software to make any changes after
you have installed the NIC. Check the documentation.
Turn off the computer and unplug the power cord.
Follow the appropriate electrostatic discharge procedures.
Remove the cover of the computer.
Install the card in a free slot.
Reconnect the computer's cables and turn on the computer before replacing
the cover. This way, if any conflicts require hardware adjustment, you
won't have to remove the cover again.
After the new hardware appears to be operating properly (you have resolved
any conflicts), replace the cover.
Install the appropriate software drivers.
Exercise 8.3: Connecting a New Computer
When you designed the network for the bicycle company, you took into account
the possibility that it would eventually be necessary to add additional
computers. That time has now arrived. The business manager has acquired
one additional computer and brought it to you unannounced. He expects you
to have it connected to the network as soon as possible so that a new employee
can begin working in two days. The computer does not have a network interface
What steps do you need to take in order to successfully connect the
new computer to the existing company network?
The following points summarize the main elements of this lesson:
Methods for installing drivers in a computer operating system vary with
the operating system used.
Manufacturers release updated drivers for their devices. These drivers
can be downloaded from the Internet or a bulletin board and installed to
provide improved performance.
Old and unused drivers should be removed to prevent conflicts.
When choosing a NIC, be sure to weigh factors such as the type of bus,
the speed of the card, and the media connection before making your decision.
Network interface card (NIC) drivers reside in the Media Access Control
sublayer of the data-link layer of the OSI reference model.