Welcome back to IT Free training free series for windows 7. In this video I will look at
how device drivers work in windows. A device driver is software installed on your computer
which communicates directly with hardware installed on your computer. By using a device
driver means that software does not need to understand how to communicate with a device
driver directly. Software on your computer only needs to understand how to access the
framework installed on the computer to access the device.
In any computer systems there are a number of devices that may it work. Most systems
will have a hard disk, sound card and a graphics card. If at some point you decide to replace
your hard disk with a raid device, you need to install the raid device driver on your
system in order to read the raid device. Assuming windows does not all ready have the device
driver available. An application running on the computer does
not interface directly with the hard disk. So changing the hard disk from a single hard
disk to a raid device does not cause any problems with the application. You could also change
the sound card and graphics card as well by simple removing the hardware and installing
the new hardware. Once complete, you need to make sure that the device driver is installed
correct for the new device. If the sound card was later changed to a different
kind of sound card, for example using a u s b sound card, no changes would be required
to any application running on the system to access the sound card.
The way the sound card works could be dramatically different from the original. For example,
the device driver for the sound card could save the sound data to the hard disk rather
then play it through a device. All this could be done completely transparently to the device.
The problem with device drivers is that they interface with the hardware of the computer
directly and thus a buggy or poorly written device driver can crash a computer system.
The blue screen of death is synonymous with badly written device drivers.
Hopefully the blue screen will happen in the office behind closed doors, however this has
not always been the case. Blue screen errors have happened on news boards, the Chinese
Olympics and even a concert just to name a few.
You will always have blue screen errors and computer crashes if the hardware on your computer
starts failing. Computers overheating and malfunctioning hardware can cause blue screen
errors. Windows in the old days developed a name for itself as being unreliable and
buggy. Looking into the crashes for windows 2000 showed that 89% of blue screen crashes
were caused by 3rd party device drivers. The development of these drivers is outside of
Microsoft's control. Microsoft did get a lot of bad press due to badly written drivers
and it was generally believed this was due to Microsoft's operating system being unreliable.
In order for windows to become more reliable something had to be done to make the device
drivers more reliable. One change that Microsoft introduced is WHQL
drivers. WHQL drivers or Windows hardware quality labs is process Microsoft runs on
3rd party device drivers. For a few hundred dollars, Microsoft will test a 3rd party device
driver with a range of hardware for one particular range of windows operating systems. Device
drivers that have gone through the WHQL process can display the logo compatible with windows
7.
Even though the cost is not to high, you could image that if you released a device driver
for a number of different operating system the cost goes up quickly. Also each time the
device driver is changed the process must be repeated and the fee paid again. For this
reason, you may see that the latest device driver released from a manufacture for a piece
of hardware is often not a WHQL driver. Using a WHQL driver means that Microsoft tested
the driver for quality and found that the device driver was reliable. Companies that
make a lot of revisions to their drivers are not going to want to pay the cost to have
every device driver tested by Microsoft for every device driver they release.
Once the device driver has completed the WHQL process, the device driver is signed using
a Microsoft certificate. Microsoft are not the only people that can
sign drivers. The manufacture of the driver can purchase a certificate and sign the driver
themselves. By doing this, when you install the driver you can be assured that the device
driver is from the manufacture and has not be changed or been corrupted.
With the release of windows X P 64 bit, Microsoft made a big change to device drivers to help
make windows more reliable. This was, they required all device drivers to be signed.
All 64 bit systems since then have the same requirement. All though it is possible to
install an unsigned driver on windows 7 64 bit, this is disabled by default.
Let's have a look at how to manage devices on windows 7.
There are a number of different ways to launch the device manager on windows 7. To launch
it from the start menu, enter in device manager and select device manager from the list. The
default view for device manager shows all the devices on your system sorted by their
type. If you have a device that is not functioning
correctly, it will appear in the list with an exclamation mark. When you perform a fresh
install of windows 7, it is a good idea to check device manager to make sure that all
the devices on the system are installed correctly. In most cases, problems like these are caused
by windows not being able to find a device driver or the device not being present in
the system. To install a device driver, right click the device and select the option update
driver software. If you have a device on your system you want
to disable, you can select the option disable. This stops the device driver from being loaded
in the system. If you system is crashing due to a device driver, disabling the device driver
may help your troubleshooting process to find the problem device driver.
You can see that when I disable the device driver, the device now has a down arrow next
to it. If you decide the you don't need the device driver installed on the system any
more, you can right click on the device and select the option uninstall. Just remember,
if the hardware is still in the system, windows may redetect the hardware and try and install
a device driver for it. Now days, windows will detect most device
when you plug them in. If you have a device driver that has not appeared, you can select
the option scan for hardware changes. This option is also available by right clicking
the root. To get more information about the device,
right click the device and select the option properties. On the first screen you can see
the status of the device. In this case the device is listed as disabled. On the advanced
tab, you can see the option for the device. In the case of a network device, you can set
option like the speed of the network adapter, the flow control and a number of different
options. Every device will be different and some devices may not have any options that
you can set. The next tab, the driver tab, gives you more
information about the driver itself. Firstly you can see the driver release date and the
version of the driver. If you select the option driver details, you can see the files that
the driver is using. If you wish to update the device driver, you
can select the option to update driver and browse to a new driver you have downloaded
or download one through windows update. If you have problems with the device driver after
you have updated it, you can select the option roll back driver to go back to the previous
driver. Next you can enabled or disable the driver
and lastly you can uninstall the device driver if you no longer require it.
On the details tab, you can get information about the hardware itself. As you can see,
there is a lot of information you can access. If you are not sure what device the hardware
is, you can select the option hardware ids. This will give you the unique hardware id's
for the device. If you put this value into a search engine, you should be able to identify
the hardware and thus find a driver for the device.
The device manager can also be used to configure resources on the computer. The auto configuration
used in windows called plug and play, has come a long way since windows 95 days. In
the old days of computers, you may have needed to configure hardware manually so two devices
were not using the same resource. This occurred because of two reasons. First resources on
the computer were more limited then what they are today and also devices were not able to
auto configure themselves as well as they can today.
If I close out of here and go to the properties for my display adapter and select the tab
resources, you can see the resources that are allocated to this device. Down the bottom
you have the option enable automatic settings which is greyed out.
Most hardware now days will auto configure themselves and resources conflicts should
be very rare. If you do have a resource conflict you can deselect the option use automatic
settings can configure the settings manually. Device manager shows only the most commonly
used devices by default. If I go into the menu and select show hidden devices, all the
devices present on the system will be displayed. Now there are a lot more devices present and
there is even a section for non plug and play devices. The devices that are shown are hidden
for good reason and it is very rare that you would need to make changes to them, but if
you do it is nice to know how to find them. If I select the option devices by connection,
you can see which devices are connected to which device. Most devices will be under the
ACPI section. The view is a little bit cluttered so I will deselect show hidden devices. On
most systems, most devices will be located under the PCI bus.
If I select the option resources by type, I can now see which resources a device is
using. If you are troubleshooting a resource conflict, which are very rare now days, this
view will help you determine where the conflict is.
In a lot of cases, using the device manager will be enough to resolve devices problems.
There are some more advanced tools to configure devices drivers available in windows 7 which
is the topic of our next video.