Device Driver Basics

Most people understand that the "hardware" partsoftware) for the PC. Should Microsoft be held
of their computer is the real physical parts, likeresponsible for the quality from a third-party?As I
the keyboard, mouse, modem, hard drive and sodescribed in Part 1 of this article, the operating
on. They understand that the "software" issystem doesn't interface directly to a hardware
computer bits stored on the hard drive, CD-ROM,device. There is a piece of software called a
or other storage media. But most people are a"driver" that translates the hardware's control
little hazy about exactly what a "driver" is.In thissignals to signals that the operating system
article, I'm going to reveal in plain English what aexpects, and translates signals from operating
driver is, why we need drivers, and exactlysystem to the hardware's control signals.
where the drivers are hiding. To give you a basicObviously, the hardware manufacturer provides
understanding, I'm going to go back, way back, tothe driver.Because the driver works between the
the early days of computers.The Early DaysTheoperating system and the hardware, a bug in the
year is 1981 and the world is in the midst of adriver can cause a serious problem. Many of the
severe resession. IBM's main frame business hasproblems with Windows have come from bugs in
slowed and the company is losing money. Up untilthird-party drivers that Microsoft had nothing to
now they had been laughing at the array ofdo with. For this reason, Microsoft created a
microcomputers on the market: Atari,Hardware Quality Lab to test drivers. A hardware
Commodore, sinclair. Toys really, mostly used tomanufacturer can submit their driver for testing,
play computer games.The problem was, theseand if it is passes rigorous compatibility testing, it
"toys" were selling like hot cakes. IBM had to getreceives Microsoft's digital signature.You may have
into that market and get into it fast. They didn'treceived a message during the installation of a
have time to design and build a computerhardware device warning that the driver was not
complete enough to compete in the market, sosigned. Why would a hardware manufacturer fail
they built an "open system". They usedto have their driver certified by Microsoft? The
commonly available electronic components andcomputer hardware market is very competitive
they published every design detail (including theand the manufacturer might want to bring a new
code), and they even provided plug in slots soproduct to market before thorough testing can
that others could build components for theirbe completed. Or maybe they don't want to or
computer.And people did provide components forcan't afford to pay Microsoft for certification. The
the IBM PC. They provided video cards, memoryquestion is, should you click on the "Continue"
expansion cards, input-output port cards, gamebutton to install the unsigned driver?In my
port cards, hard disk interface cards, and muchexperience, I have never been able to trace a
more. How were all these various devices able toproblem to an unsigned driver. If it's your home
interface with the PC's operating system? That'scomputer and you performed a back-up recently,
where a "driver" comes in.A hardware device isgo ahead and install the unsigned driver. If it's a
constructed with various electronic componentscomputer on a corporate network, you may
using various control signals, but the softwarewant to back-out of the installation and see if you
interface to the operating system is standardized.can locate a signed driver first. Many times a
A device's interface to the operating systemmanufacturer will release a product with an
must follow the interface specification. A driver isunsigned driver, then later provide a signed driver
a piece of software that translates theas a free download from their website.If you
hardware's control signals to signals that thedecide to go ahead and install an unsigned driver,
operating system expects, and translates signalsyou can always update the driver later. If your
from the operating system to the hardware'scomputer works with the unsigned driver, I would
control signals.When the computer is started up, itnot update the driver. When it comes to updating
would look in the "system" directory for files withdrivers (or the computers BIOS) I go by the old
the extension ".drv" and load them into memory.saying, "if it ain't broke don't fix it".To update a
Specific files like autoexec.bat, config.sys, anddriver, select Start | Settings | Control Panel and
win.ini were used to inform the operating systemdouble-click on the "System Properties" Utility. In
about drivers. Hardware would be configuredthe "System Properties" Utility, select the
through these files, or through jumpers located on"Hardware" tab and click on the "Device Manager"
the device itself.The driver specification evolvedbutton. In the "Device Manager" window, right-click
along with the PC. Today when a PC starts, iton the device in the list and select "Properties" in
executes the program which queries thethe popup menu. In the "Properties" dialog box,
hardware components and builds the registeryselect the driver tab and click on the "Update
keyDriver..." button.In the "Properties" dialog box
entControlSet. This key exists only in memorydriver tab, you may have noticed the "Roll Back
and is created each time the computer boots. IfDriver" button. If your computer has problems
all the drivers are loaded successfully, a copy ofwith the new drive, you can click on the "Roll
the key is saved as ControlSet00X.Under theBack Driver" button to roll back to the previous
registery key CurrentControlSet, the subkeythe driver. Driver roll back saves only one
"Enum" contains a subkey for each harwareprevious driver, so if you update a driver, then
device on the computer. Each device key containsupdate it again, the original driver is gone. If the
fields for Hardware ID, Driver ID, Devicecomputer has problems with the new driver,
Parameters, and other configuration data. Thealways roll back to the original driver before trying
32-bit drivers are files with the extension ".sys"a different one. That way you'll always have the
and can be found in the folder C:/winntoriginal driver to roll back to.Copyright(C) Bucaro
system32.Driver SigningMicrosoft has been theTecHelp.Permission is granted for the below article
brunt of much criticism because of the poorto forward, reprint, distribute, use for ezine,
reliability of the Windows Operating System. I feelnewsletter, website, offer as free bonus or part
that much of this criticism is justified. On theof a product for sale as long as no changes are
other hand, as I described in part 1 of this article,made and the byline, copyright, and the resource
the PC was designed by IBM as an "open"box below is included.
system. Anyone can sell a hardware device (or