Hi Emily,
The following document was given out at the CSUN conference in March. It
will apply the next time you upgrade JAWS or ZoomText under Windows XP or
Windows 2000, if it does not apply now.
Jay Leventhal
Editor in Chief, AccessWorld
http://www.afb.org/accessworld.asp
Microsoft and Partners Team Up to Solve Driver Chaining
Microsoft and partner organizations Ai Squared, GW Micro, Freedom
Scientific and Dolphin Computer Access are solving what has become more
than a nagging problem for users of assistive technology aids. The problem
-- driver chaining — can cause boot failures, system crashes and
malfunctioning software when multiple assistive technology aids are
installed on the same computer. The solution — Driver Chain Manager 1.0 —
reduces the occurrence of errors by organizing the interaction of the
drivers involved in screen reading and screen magnification.
Solution Overview
Assistive Technology
Ai Squared ZoomText 7.11 with driver utility program and ZoomText 8.0
Dolphin Computer Access Hal 5.20, Lunar 5.20 LunarPlus 5.20, and Supernova 5.20
Freedom Scientific JAWS 4.51 and MAGic 8.1
GW Micro Window-Eyes 4.21
At a Glance
Having multiple assistive technology aids installed on the same computer
can lead to boot failures, system crashes, and malfunctioning software. The
source of the problem is a display driver interception technique known as
driver chaining. In response to the problem, Microsoft and four partner
organizations have come together to develop a solution — Driver Chain
Manager 1.0.
Compatible Microsoft Products
Microsoft® Windows NT®, 4.0
Microsoft® Windows® 2000
Microsoft® Windows® XP
Benefit
Reduces crashes, boot failures and malfunctioning software caused by driver
chaining.
Allows installation of multiple assistive technology aids that use the
display driver interception (DDI) technique.
Assistive Technology Users Install Multiple Aids on the Same Computer
With the wealth of assistive technology aids now available, it's natural
for users of such aids to want as many as possible in order to simplify and
enrich their computing experience. A user might, for example, want to
install several screen readers and magnifiers as well as trial software on
the same computer. Having multiple assistive technology aids installed in
the same computer is where the problem begins.
The Issue with Screen Readers and Screen Magnifiers
Screen reading and screen magnification software works by locating the
display driver, getting the information about what is drawn on the screen,
then passing the sometimes modified display driver interface (DDI) calls to
the original display driver. (Certain remote control software also uses
this technique to intercept information being passed to a remote computer.)
The DDI interception technique is called driver chaining. Some drivers,
such as screen readers, pass through information to the next driver in the
chain, so subsequent drivers work correctly. Other drivers, such as those
for screen magnifiers, modify the information when they are active (they
magnify it), causing the drivers that follow them to work incorrectly.
The Problem with Driver Chaining
For the most part, driver chaining is not recommended because a driver is
never meant to be replaced or modified, and DDI calls are not meant to be
intercepted. Having multiple chained drivers each handling DDI
interception calls for an individual screen reader or magnifier only
complicates the situation. At present, however, driver chaining is the only
way for screen reader and magnifier software to get full information about
what is drawn on the screen.
A major problem with driver chaining today is the absence of rules
governing how drivers work with each other. Consequently, chain drivers are
not always aware of each other's existence; a given driver may not know
what other driver precedes or follows it. When there is a long set of
drivers chained together, the last driver in the sequence is the actual
driver known to and used by the system to write to the display hardware.
Driver chains often become so corrupted that the system can no longer find
the "real" display driver and, therefore, defaults to VGA mode or becomes
unstable and crashes.
The Driver Chain Manager Solution
Driver Chain Manager 1.0 is a set of library routines, aimed primarily at
screen readers and magnifiers, used by each DCM-enabled assistive
technology aid to install, remove and maintain its graphics driver
interceptors. Because a common library is used, installation and removal of
interceptors for different assistive technology aids is done in a
consistent manner. This set of standards for DDI interceptors brings order
to chained drivers and allows them to work cooperatively.
DCM 1.0 Capabilities
· All DCM chain drivers use the same escape code to handle
communication between their user and driver modules.
· The active DCM chain driver regardless of its position in the
chain will not be impacted by other DCM chain drivers, provided only one
driver is active at a time.
· A user can install and uninstall DCM chain drivers in any order
without affecting the other drivers.
· The latest version of the DCM Library is installed automatically
(in the same manner as Microsoft Active Accessibility) when you install or
upgrade an assistive technology aid that is DCM-enabled.
· If the display adaptor is changed, it is detected so proper
adjustment of the chain can be carried out.
· There are workarounds for common remote control software that rely
on chaining.
FAQs
What is Driver Chain Manager?
DCM 1.0 is a new technology whose purpose is to allow multiple assistive
technology aids to be installed in the same computer. DCM is aimed
primarily at screen readers and screen magnifiers.
Can DCM functionality be used by other software products?
Yes. Microsoft intends to promote DCM to other vendors whose products
perform display driver interface calls. If other vendors use DCM, their
products should become more compatible with assistive technology aids.
How does DCM 1.0 work?
DCM is a set of library routines used by each assistive technology aid to
install, remove, and maintain graphics driver interceptors. Because a
common library is used, installation and removal of interceptors is done in
a compatible manner between different assistive technology aids.
What problem does DCM 1.0 solve?
The primary problem that DCM solves is allowing users to have multiple
assistive technology aids installed on the same computer.
Does DCM 1.0 allow multiple aids to be run simultaneously?
The purpose of DCM 1.0 is to enable multiple aids to be installed on the
same computer. DCM does not guarantee that multiple chained drivers will
function properly when running at the same time.
For More Information About
Accessible Technology
Discover how your business can benefit from accessible technology today.
For more information, call
1-800-MSPRESS, visit your local
or online bookstore, or go to www.microsoft.com/mspress/
books/5588.asp.
About Ai Squared
Ai Squared was founded in 1985 with a fairly simple idea to make
computers more accessible to low-vision users. The result was ZoomText,
first released in 1988. ZoomText quickly became the industry standard in
Windows-based screen magnification, and now, 17 years later, ZoomText is a
world leader in screen magnification and combined magnification and screen
reading.
About GW Micro
Founded in 1990 and based in Fort Wayne, Indiana, GW Micro is an assistive
technology company that continues to produce high-quality, user friendly
screen reading products for individuals who are blind or visually impaired.
Window-Eyes gives users total control over what they hear, how they hear
it, and how they feel it (via synthesized speech and refreshable Braille)
for the Microsoft Windows operating systems.
About Freedom Scientific
Freedom Scientific is the world's leading manufacturer of technology
products for those who are blind and vision impaired, and products for the
special education and learning disability markets.
About Dolphin Computer Access
Developers of the award-winning Supernova Reader Magnifier, Dolphin
provides integrated magnification, speech, Braille and color management
solutions for computer users with all levels of vision impairment.
Dolphin's international software range offers access to Microsoft Windows
environments from home PCs and laptops to local and wide area networks.
© 2003 Microsoft Corporation.
All rights reserved. Microsoft and Windows are registered trademarks of
Microsoft Corporation. The information contained in this document
represents the current view of Microsoft Corp-oration on the issues
discussed as of the date of publication. Because Microsoft must respond to
changing market conditions, it should not be interpreted to be a commitment
on the part of Microsoft, and Microsoft cannot guarantee the accuracy of
any information presented after the date of publication. This document is
for informational purposes only. MICROSOFT MAKES NO WARRANTIES, EXPRESS OR
IMPLIED, IN THIS DOCUMENT.
---------------------------------------------------------------------------------
At 02:06 PM 6/16/2003 -0400, Emily Hallett wrote:
>How do I get these two programs to work together?!
>
>Machine Stats:
>
>GX 260 Dell
>video card
>
>
>I got the programs to work together once...but then it crashed my
>system and I had to reinstall the OS XP. So I tried it again and it
>crashed our Novell login screen. The computer is on a novell network
>and has a login screen...it broke the novell login screen and then I
>tried to reimage it using Zenworks imaging program and now it is not
>working.
>
>Any ideas?
>
>Emily Hallett
>Assistive Technology Specialist
>University of Southern Maine
>96 Falmouth Street
>144 Luther Bonney Hall
>Portland, ME 04104
>207-780-4182
>
>
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VICUG-L is the Visually Impaired Computer User Group List.
To join or leave the list, send a message to
[log in to unmask] In the body of the message, simply type
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