CODI: Cornucopia of Disability Information

Cornucopia of Disability Information

Considerations in the Design of Computers
to Increase Their Accessibility
by Persons with Disabilities


Version 4.2
May, 1988




This document has been prepared by the Design Considerations Task
force of the Industry/Government Cooperative Initiative on Computer
Accessibility. It is designed to be purely informational in nature,
and has been developed at industry's request, to facilitate their
efforts in this area. It represents the compilation of information
from many sources and, as a working document, is under continual
revision. No endorsement of the contents by any particular group
should be inferred.

If you received this document directly from the Design Considerations
Task Force (in a Trace Center envelope), you are on our mailing list
and will continue to receive new information as it is developed. If
you received your copy from someone else, you are probably not on our
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in the future, please send a note with your name and address to the
Trace Center:

Industry/Government Computer Accessibility Task Force
Trace Center
2107 Engineering Centers Bldg.
1550 Engineering Dr.
Madison, WI 53719

Background on the Industry/Government Initiative


In 1984, the Office of Special Education and Rehabilitation Services
(U.S. Department of Education), in conjunction with the White House,
took the initiative to begin a process of bringing computer
manufacturers, developers and consumers together to address the
question of access and use of standard computer and computer software
by persons who have disabilities.

The first meeting of the initiative was held on February 24, 1984 at
the White House. The objective of the first meeting was to
familiarize the companies with the problem and to solicit their
support for a cooperative effort to address the problem. The result
of the first meeting was a recognition of the problem, and a request
by the manufacturers for more information about the types of
disabilities, the resulting barriers to the use of standard computers,
and the types and scope of the solution strategies that the
manufacturers were being asked to consider.

Subsequent to the meeting in February at the White House, briefings
were held with manufacturers, and a White Paper was developed,
distributed for comment, and revised and distributed in preparation
for a second meeting held on October 24-25, 1985. This meeting
consisted of a one and one-half day work session followed by a
reporting session at the Rayburn Building on Capitol Hill. Computer
firms represented included Apple, AT&T, Digital Equipment Corp.,
Hewlett Packard, Honeywell, IBM, and Tandy (Radio Shack).

One of the four results of this meeting in October was the formation
of a task force to identify, refine, and document ideas and
considerations for the design of standard computers to increase their
accessibility by disabled and non-disabled people. This group is open
to any researchers, manufacturers, and consumers who want to work with
this group. The objective of this cooperative industry-rehabilitation
group is to develop materials for industry that can be used to improve
the design of computers so that they will be usable by a larger
portion of the population. The primary focus of this task force is
the development of the design information to increase accessibility.
This includes information regarding the disabilities, their impact,
the specific problems currently encountered, future anticipated
problem areas, and existing or suggested design strategies as they are

The overall computer access effort is being coordinated by the
Electronic Industries Foundation and the Trace Center at the
University of Wisconsin-Madison and is supported by grants G008300045
and G0083C0020 of NIDRR (OSERS - Department of Education). The task
force (of the Industry/Government Committee) is being coordinated out
of the Trace Center. Membership in the task force is open to anyone
who would like to participate. All task force work is done via mail
to maximize participation by all interested parties. You may become a
task force member simply by dropping a note to the task force, care of
the Trace Center, S-151 Waisman Center, 1500 Highland Avenue, Madison
WI 53705.


+ A significant portion of our population has disabilities
(acquired at birth or through accident, illness or natural aging)
which prevent them from using standard microcomputers and software.

+ Many low-cost and no-cost modifications to computers would
greatly increase the number of individuals who could use standard
computers without requiring modifications.

+ In addition, other modifications would greatly increase the
ability to attach special input and output systems, further increasing
the number of individuals who can access and use standard computers
and software (as well as lowering the cost for such modifications).

+ Most of these design changes fall in the low-cost or no-cost
range, and have direct benefit to the mass market as well.

+ The current direction in which computer systems are evolving will
automatically encompass many or most of the required features and
capabilities if the new design directions are implemented carefully.

+ In discussions with engineers and designers within the major
computer companies, the predominant response has been that many of the
desired changes could have been included in the design of computers
originally if the developers had been aware of the need for and impact
of such changes.

+ The purpose of this Design Considerations document is to provide
an awareness of the different types of problems, as well as design
recommendations for increasing the accessibility of new computers.

Disability Types and Barriers

+ Physically impaired individuals face their primary difficulty in
using the computer's input devices, or in handling storage media.
Individuals in this group include individuals with congenital
disabilities, spinal cord injuries, and progressive diseases, as well
as individuals who are without the use of just a hand or arm. Adding
some options to the keyboard handling routines would allow many
individuals to use the keyboard. Providing means to connect
"alternate keyboards" would provide access for individuals who have
more severe disabilities.

+ Visually impaired individuals have their primary difficulties
with the output display, although newer display-based input systems
(e.g., mice, touchscreens) may also pose problems. This group
includes individuals who have failing vision and individuals with
partial vision, as well as those who are blind. The primary solution
strategies involve providing a mechanism to connect alternate display
or display translator devices to the computer, and providing
alternatives to display-based input.

+ Hearing impaired and deaf individuals currently have little
difficulty in using computers. Visual redundancy of auditory clicks
and tones would be helpful. The primary concern is ensuring that
future voice output information is provided in a redundant form that
hearing impaired or deaf individuals can also understand.

+ Cognitively impaired individuals have their greatest difficulties
in dealing with the software itself, although layout and labeling of
operational controls can also effect their ability to use computers.
Cognitive impairments can take many forms, including retardation,
short- or long-term memory impairments, perceptual differences,
learning disabilities, and language impairments. Of particular
concern are computer, information or transaction systems which are
intended for public use. Proper design of these systems can greatly
increase the number of individuals with mild cognitive impairments who
could use the systems -- although these systems may not be operable by
individuals with severe impairments. Solution strategies in this area
would be more general in nature, and revolve around such objectives as
simplification of displays and legends, minimization of language
level, and obviousness of operation.
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Part II:

Detail and Notes
for Design Recommendations
Table of Contents: Part II

.Begin Table C.

Design Considerations for Individuals
with Moderate Physical Impairments (P) 12

Item P1: Sequential Option if Simultaneous Actions Are Normally
Required 13

Item P2: Timed Responses Adjustable or Defeatable 15

Item P3: Alternate Method for Achieving Input Normally Done with a
Pointing Device 16

Item P4: Media (Removable) Should Be Easily Inserted and Removed

Item P5: Controls and Latches Easily Accessible and Operable 19

Item P6: Keyguard and/or Delay Before Acceptance of Keyboard Input

.End Table C.

.Begin Table S.

Design Considerations for Individuals
with Severe Physical Impairments (SP) 23

Item SP1: Alternate Input Connection Points -- External and Through
System 24

.End Table S.

.Begin Table V.

Design Considerations for Individuals
with Visual Impairments (V) 26

Item V1: Screen Image Enlargement Capability 27

Item V2: Display Colors Adjustable 29

Item V3: Easily Readable Letters on Keys and Important Controls 30

.End Table V.

.Begin Table B.

Design Considerations for Individuals
Who Are Blind (B) 31

Item B1: Display Data Available at External Connection Point -- and
through System 32

Item B2: Alternative to Eye-Hand Coordination Input Devices Where
Possible 34

Item B3: Nonvisual Indication of Toggle Keys' State 35

Item B4: Nonvisual Key Labelling 37

.End Table B.

.Begin Table H.
Design Considerations for Individuals
Who Are Hearing Impaired or Deaf (H) 39

Item H1: All Audible Output Also Provided in Visual Form 40

Item H2: Audio Output Should be Adjustable as well as being Available
in a clear form for Amplification 42

.End Table H.

.Begin Table E.

Design Considerations For Individuals
Who Have Seizure Disorders (S) 44

Item S1: Displays and Software Avoid Some Refresh and Update
Frequencies 45

.End Table E.

.Begin Table M.

Design Considerations that Would Facilitate
Development of Computer Access Devices
by Third-Party Manufacturers (M) 47

Item M1: Manuals Available in Electronic Form 48

Item M2: Speech Output Compatible 49

Item M3: Special Display Window Which Can Stay Visible (on top) 50

Item M4: Connection Point for Switches or Transducers 51

Item M5: Method for Distinguishing Macro Input from Keyboard Input

Item M6: Keyguard or Keyguard Mounting Provision 53

.End Table M.




Design Considerations for Individuals
with Moderate Physical Impairments (P)


Physically disabled individuals face their primary difficulty in using
the computer's input devices, or in handling storage media. People in
this group include persons with congenital disabilities, spinal cord
injuries, and progressive diseases, as well as people who are without
the use of just a hand or arm. Adding some options to the keyboard
handling routines would allow many individuals to directly access the
Item P1: Sequential Option if Simultaneous Actions Are Normally


Some individuals who can use only one arm or hand (temporarily or
permanently) or who use a headstick or mouthstick cannot activate
multiple buttons or keys at the same time.


+ Individuals with one arm or those who use a mouthstick cannot use
shift/control/option keys on standard keyboards. . .
. . . or operate a mouse while they hold down a shift/control/option
key. . .
. . . or operate a multi-button mouse.


Input devices that require multiple simultaneous activations should
have an optional (sequential) mode of operation. This mode should be
available at any time, and should eliminate the need for simultaneous


RECOMMENDED EXCEPTIONS: 1) Input buttons/keys requiring co-activation
for physical safety reasons; 2) input buttons/keys not required for
normal operation;

Current GSA Guideline

"Multiple Keystroke Control. Currently there are numerous common
functions on the computer that require multiple, simultaneous
keystrokes (e.g., to reboot CTRL+ALT+DEL must all be depressed at the
same time). Multiple keystroke control would enable the user to
execute a sequential option in which multiple keystrokes could be
entered serially (e.g. to reboot a user could depress CTRL, then ALT,
then DEL)." (Current GSA - Initial Guidelines, October, 1987)


1) This is the only major computer access barrier faced by many
individuals with mild to moderate handicapping conditions (such as
many with spinal cord injuries), and one which can be easily

2) This feature applies to input devices and controls needed for
computer operation only, and is not meant to apply to periodic
adjustment, maintenance, set-up, or materials replacement aspects of
the equipment, such as changing ribbons or paper, removing jams, etc.,
although these capabilities are also useful.

3) A "Sticky Key" feature could be added to the keyboard to solve
this problem. Recommended implementation for Sticky Keys is:

+ Sticky Key feature invoked by tapping five times in a row on
either shift key.

+ Once activated, touching any modifier key (shift, control, etc.)
followed by another key will be presented to the system and
application software exactly as if the modifier key and the other key
were pressed concurrently. Immediately after the other key is
pressed, the modifier key is automatically released.
+ Depressing a modifier key twice in a row causes that modifier to
"lock down" until the modifier key is pressed a third time.

+ Any time any a modifier key and another key on the keyboard are
depressed simultaneously, the feature immediately deactivates and the
keyboard returns to normal operation. (Thus, the feature would
automatically disappear if a normal typist began using a keyboard on
which the feature had been active.)

+ The feature can also be turned off by hitting the shift key five

+ In systems that use a "shift click" feature (where the shift key
is depressed while the mouse key is activated), the "Sticky Key"
feature should work in conjunction with the mouse.

+ In systems with mice or other devices having multiple buttons
that are sometimes held down simultaneously, alternate sequential
activations should be provided.

+ If there are two modifier keys with the same function (e.g., two
alternate keys) that can be distinguished as two separate keys by the
operating system or software, then they should behave as if they are
two separate Sticky Key keys (to allow the disabled user to activate
programs which ask the user to depress two shift keys simultaneously
to invoke special features or functions). If one of the keys is
locked, however, hitting the other key should release the locked key
(in case the user cannot remember which key they locked).

+ Whenever possible some indication (visual and/or auditory) of the
key status should be provided) (Auditory indications should have
visual alternative - see Item H1.)
Item P2: Timed Responses Adjustable or Defeatable


Some individuals with poor coordination have slower or irregular
reaction times, making time-dependent input unreliable.


+ The normal key repeat rate is too fast for some users, resulting
in undesired characters.

+ Programs that require a response within a short period of time or
that utilize modes that shut off automatically or reset too quickly
may also cause problems.


Systems requiring responses in less than 5 seconds, or a release of a
key in less than 1.5 seconds, should include a provision for the user
to adjust the time interval, or to have a non-time-dependent alternate

PRIORITY: 1 - Individuals with slow response times need this ability
in order to operate the equipment.

Current GSA Guideline

"Keyboard Repeat Rate. Currently the computer generates repetitions
of a character if the key is held down. This is a problem for those
users without sufficient motor control of their fingers to conform to
the repeat tolerances of the keyboard. This feature would give the
user control over the repeat rate. The user could extend the keyboard
tolerances or turn off the repeat function completely."


1) The key repeat rate adjustment option should include both the
start delay and the repeat delay, as well as the ability to turn the
repeat feature off.

2) Rates should be adjustable in five or more steps which vary the
time interval in a nonlinear fashion.
Item P3: Alternate Method for Achieving Input Normally Done with a
Pointing Device


Some individuals do not have enough fine movement control to use some
of the newer input methods, such as the mouse, touchscreen, etc.


+ Individuals with paralysis of the hands or motor coordination
problems cannot accurately use a mouse, touchpad, joystick, trackball,
or touchscreen.

+ Individuals who use a mouthstick, or those using special
keyboard-simulating input systems, cannot operate a mouse or other
analog pointing device.


Systems having mice or other pointing systems should have a method for
carrying out all of the same functions from the keyboard.


Current GSA Guideline

"Input Redundancy. Currently numerous programs use a mouse as one of
the input options. As the use of graphics increases so will
dependence on the mouse as an input device. Some users with
disabilities cannot use a mouse. This feature would provide an
emulation of the mouse using the keyboard and/or other suitable
alternative input devices, e.g. joy stick, trackball, voice input, and
touchpad. In effect, any movement control executed through the mouse
could also be executed from alternative devices."


1) This recommendation could be satisfied through a user-invokable
operating system option which would use part of the keyboard to
control the mouse cursor and mouse buttons, or to create simulated
touchscreen and touchpad input, etc.

2) Systems that allow keystrokes as an alternate to mouse pointing
help with, but do not fully solve this problem (e.g., rather than
clicking on a cancel button, the individual can type a "C").

3) The use of cursor arrow keys to move through different options in
dialog (set-up or adjust) boxes also assists with this problem.

4) Systems that are designed such that all mouse-activated functions
can also be activated from the keyboard may satisfy this need.

5) Keyboard alternatives to mouse operations are frequently useful
to the regular nondisabled user population as well.
Item P4: Media (Removable) Should Be Easily Inserted and Removed


Some individuals with poor motor control or limited strength or manual
dexterity (including those with no hand use) have difficulty grasping
or handling materials delicately.
Some individuals are unable to reach built-in media drives because of
their position relative to the drive location.


+ Individuals with cerebral palsy often damage media surfaces or
bend flexible floppy disks.

+ Individuals with limited reach or strength cannot reach built-in
drives, especially on floor-mount computers.

+ Individuals with cerebral palsy, spinal cord injury, arthritis,
etc., have difficulty reaching into floppy, CD ROM, and other media
drives to remove media.


Removable media drives should allow media insertion and removal with
minimal reach and manual dexterity.

PRIORITY: 2 - Increases efficiency of worker by removing the need to
call for assistance each time removable media must be handled.

Current GSA Guideline:



1) This is most important in environments where diskettes, CD ROMs,
and other removable media are exchanged regularly in the drive. It is
less important when programs and data are accessed by modem or
network, or from a local hard drive.

2) Removable media should be able to withstand fairly rough
handling, and should preferably be "hard cased" to accept light

3) Removable media should eject and/or protrude a minimum of 3/4" to
1 1/2" from the drive when unloading. This is true clearance beyond
any frame and cover overlap. A clearance near or above the upper end
of this range is preferred. Distances beyond 1 1/2" are desirable
where possible.

4) Removable media drives which are available in external mount
configurations allow special positioning of the drives for easier

5) Media/drives should be self-guiding, loading and unloading from
the front by pushbutton or software ejection.

6) Pushbutton ejection systems, particularly those that can be
operated with low pressure, help to address this problem.

7) Ejection buttons that are concave rather than flat are much
easier to operate with a mouthstick or headstick.

8) Drives that involve a twisting motion are difficult to use.
9) Hard cases such as those on 3 1/2" disks are very helpful here.
Item P5: Controls and Latches Easily Accessible and Operable


Some individuals who are weak, have poor or no use of their hands, or
have limited reach have difficulty accessing and manipulating some
conventional controls (or moving equipment in order to access


+ Individuals with limited reach are unable to operate switches or
controls located at the rear of the computer.

+ Individuals with limited dexterity (arthritis, cerebral palsy,
etc.) are unable to use latches or controls that require twist motion.

+ Individuals with use of only one hand cannot open some laptop
computers with dual latches which must be simultaneously released.

+ Individuals with low strength (MS, MD, and spinal cord injury)
are unable to operate controls that require very much force (much more
than 100 grams).

+ For severely physically handicapped persons who are using
alternate special keyboards (sip and puff keyboard, Morse code
keyboard, eye gaze operate keyboard, etc.), only controls that can be
operated from the keyboard would be accessible.


Controls (and latches) which are required on a regular basis for
system operation should be accessible and operable with minimum

PRIORITY: If only occasional adjustments are involved, then it is a
Priority 3. If controls are needed for ongoing operation rather than
occasional adjustments, then they would be Priority 1.

Current GSA Guideline



1) This becomes less critical if a control is for an adjustment that
is only occasionally used.

2) The following are good features for controls (all light action):

+ Controls located at the front edge of the equipment

+ Pushbutton controls (preferably concave) requiring less than 100
grams of pressure

+ Sliding or edge-operated controls

+ Up/down (integrating) control buttons

+ Double-acting pushbutton controls

+ Rocker switches (concave)

+ Controls that are operable from the keyboard are best (e.g.,
volume, display and printer controls, power - "sleep," etc.), since
they also facilitate access to these controls by individuals who are
using alternate or substitute keyboards (future systems)

3) The following should be avoided:

+ Placement requiring the user to lean around the side or back of
the equipment to see or operate the controls

+ Controls requiring twist or push-and-twist in combination

4) A good rule of thumb is

Item P6: Keyguard and/or Delay Before Acceptance of Keyboard Input


Some individuals with limited movement control can inadvertently bump
extra keys on their way to the desired key(s).


Individuals who have difficulty in eye/finger (eye/stick) coordination
often strike unwanted keys before targeting the desired key. This
includes individuals with tremor, incoordination, or those using
headstick or mouthstick.


A special option (difficult to accidentally invoke) could be provided
that would delay the acceptance of a keystroke for a preset,
adjustable amount of time, and/or a keyguard or keyguard mounting
provision could be provided.

PRIORITY: 4 - Individuals with this difficulty can use a third-party-
supplied keyguard. Also, presence of this feature can be mistaken for
a broken keyboard (see below).

Current GSA Guideline

"Keyboard Orientation Aids. . . . To assist a motor disabled user, a
keyguard should be available to ensure that the correct keys are
located and depressed. A keyguard is a keyboard template with holes
corresponding to the locations of the keys."


1) The recommended software option would require any key to remain
depressed for a continuous interval of time before it was recognized
by the system. This option should be designed so that it must be
purposefully loaded and activated each time, as a patch to the
keyboard system from a special diskette. It is not recommended that
this be a standard system option, as it has the potential for causing
the keyboard to appear to be broken (see below).

2) Once the feature is invoked, the keyboard will look "broken" to a
normal user, especially if the delay is of any significant length.
This is because when the normal, nondisabled user taps on the keys in
the normal fashion, nothing happens (since the keys do not stay down
long enough).

Even if the delay is set to a short period of time, the keyboard may
still appear faulty. If a person is typing at normal speed, , few if
any keys will be accepted, causing the keyboard to behave as if the
keys are broken or erratic. If the individual hits the keys harder,
however, the keys may appear to work (since pressing keys harder also
causes them to be depressed longer).

It is therefore recommended that this feature not be included as a
standard feature, but rather be treated as a specially loaded utility.
Furthermore, it is recommended that when invoked, a large sign appear
on the display, warning of the consequences as well as the "symptoms"
of the feature when viewed by normal typists (especially in a shared
user environment). This sign should remain on the screen until a
confirming key is struck, to avoid missing the message if someone put
the routine into an autoexec batch file.




Design Considerations for Individuals
with Severe Physical Impairments (SP)


For individuals with more severe physical handicaps, modifications to
the standard input devices are not sufficient to allow them to use the
computer. For these individuals, some mechanism for connecting
alternative keyboards, mice, and other input devices is required.

Item SP1: Alternate Input Connection Points -- External and Through


Some individuals with severe physical impairments must use special
devices and programs (simulating keyboard, mouse, and touchpad input)
in order to use the system.


+ Individuals who require an eyegaze or sip-and-puff controlled
input cannot connect their device in place of the normal input devices
(keyboard, mouse, touchscreen, etc.)

+ Scanning and other special input programs can be designed which
would run in the background (or under multitasking) and replace the
keyboard function. These systems, however, do not have a standard
means to inject simulated keystrokes, touchscreen or mouse activity
into the computer for use by the operating system and application
programs. This inability on the part of the operating system to allow
simulation of input device activity prevents the use of low-cost
software solutions that provide alternate input systems for those who
require them.

+ When computer systems are changed or upgraded, or when an
individual changes jobs, their special input devices usually will not
work on the new computer/model. Architectural considerations that
facilitate transportability of such alternate input systems between
operating systems and/or work station models is needed.


a) Systems should have an externally available connection point(s)
(standard or special port{s}) for adaptive input devices; the
connection should be an industry or company standard; and the computer
should treat the input from the adaptive devices the same as input
from other standard input devices such as keyboard, mouse, or tablet.

b) This ability to simulate input device activities should also be
available to programs running in background on computers which support
background processing or multitasking.

PRIORITY: 1 - Severely physically impaired persons are unable to
access computers if no provision is made for connecting alternate
input devices and programs.


"Alternative Input Device. The capability to connect an alternative
input device would be available to the user who is not able to use a
modified, but standard keyboard. This feature would supplement the
keyboard and any other standard input system used. The alternative
input capability would consist of a physical port (serial, parallel,
game, etc.) or connection capability so that an accommodation aid
could augment the keyboard or replace it. The computer would regard
this device as its keyboard and the user would be able to input any
valid keystroke combination (e.g. CTRL + ALT + DEL) available from the
regular keyboard. This alternative input capability would also
support the mouse emulation described above." (previously discussed,
in Item P3)


1) One way that part (a) of this recommendation could be satisfied
is by a system command which would cause input from a standard serial,
parallel or other system port to be treated by the system and
application programs exactly as if it had come from the computer's
standard input devices (keyboard, mouse, etc.).

2) One way that part (b) could be satisfied would be for the
operating system to have an "inject only" (write only) point or
address to which simulated input could be sent. This injection point
would have to be in front all system or program processing of the
input, so that anything done through the standard input devices
(including reset and switching between programs in a multitasking
system) could be accomplished through this "injection point."

3) Blind individuals may not be able to access newer mouse or
display-based computers without the ability to have their special
display systems and/or programs simulate mouse or other types of
display-based input.




Design Considerations for Individuals
with Visual Impairments (V)

Visually impaired individuals have their primary difficulties with the
output display, although newer display-based input systems (e.g.,
mice, touchscreens) which require eye hand co-ordination also pose
problems. This group includes individuals who have failing vision and
individuals with partial vision.
Item V1: Screen Image Enlargement Capability


Some visually impaired individuals have difficulty seeing normal sized
text and graphics images on the screen.


Individuals with low vision have difficulty reading the screen because
the characters (text) and images are too small.
Individuals with low vision have difficulty seeing the screen due to
glare or distance.


Microcomputers should provide a means for

a) attaching larger (and repositionable) displays, and

b) for enlarging the image on the display.

PRIORITY: 1 - Some means for connecting larger displays is necessary.
A built-in zoom enlargement feature can reduce or eliminate the need
for high cost or custom screen image enlargement equipment.


"Large Print Display. This feature increases the size of a portion of
the screen for the low vision user. The process might use a window or
similar mechanism that allows magnification to be controlled by the
user. The user could invoke the large print display capability from
the keyboard or control pad for use in conjunction with any work-
related applications software. If applications software includes
graphics, then enlargement of graphics should also be available."
(Current GSA - Initial Guidelines, October, 1987)


1) A standard video connector or a slot that allows connection of a
video controller card should satisfy part (a) of this recommendation.

2) Modification to the basic display support that would allow the
user to "zoom" on any area of the screen would address part (b) of
this recommendation.

3) Such a "zoom" feature would be most useful if the enlarged image
could automatically track cursor movement during data entry, as well
as pointing device (e.g., mouse) movement (real or simulated).

4) A zoom enlargement feature should be able to enlarge any area of
the screen, and provide magnification up to 16 times original size, in
at least 8 steps.

5) If the display contains both text and graphics, the zoom feature
should work on any portion of the image.

6) If a very small cursor is used (e.g., an underline or a thin
vertical line), it is helpful to have a means for substituting a
larger cursor and/or causing the cursor to blink.

7) The above zoom capability might initially be provided by building
"hooks" into the appropriate operating system functions that third-
party manufacturers could use to write special zoom programs (although
it would be useful to have some zoom capability built into the
operating system itself).
8) If text-only screens are used, a useful option would be to allow
the text to be reformatted into long, narrow columns (based upon the
magnification selected) so that the user need only scroll in the
vertical direction while reading text.

9) Advanced zoom features might include a split-screen option to
allow two non-adjacent parts of the display to be viewed
simultaneously (especially for database/spreadsheet programs).
Item V2: Display Colors Adjustable


Some color blind end users have difficulty distinguishing some color
pairs, such as green and red.


+ Color blind individuals cannot see text presented in some text-
background color combinations.

+ Color blind individuals may not notice highlighted words when
they are highlighted with a color and have no other distinguishing


Where the color of graphics or text must be distinguished in order to
understand information on the display, end users should be able to
select the colors used.

PRIORITY: 1 - If color differentiation is required to operate the
system, then individuals who cannot distinguish colors will not be
able to operate the system.

Current GSA Guideline

"Color Presentation. Where colors must be distinguished in order to
understand information on the display, color-blind end users should be
able to select the colors displayed." (Current GSA - Initial
Guidelines, October, 1987)


1) If information is discernible in grey scales on a black and white
screen, then a monochrome display mode would satisfy the

2) If the colors chosen are of sufficiently different intensity
(light yellow versus dark red) that they would be distinguishable as
different shades even to a color blind individual, this recommendation
would be satisfied. Similarly, if the colors and intensities were
chosen such that they were distinguishable by individuals with all
types of color blindness, the recommendation would be satisfied.

3) Choice of colors for all key labels and other documentation
should take into account the limitations of color blind individuals.
Item V3: Easily Readable Letters on Keys and Important Controls


Some visually impaired individuals have difficulty identifying keys
and operating controls with existing (small) lettering.


Individuals with low vision have difficult reading keys with small
labels. They also have difficulty reading controls which use small
lettering or low contrast colors.


Lettering on keys and controls required for operation should be easily

PRIORITY: 2 - Large, easily readable lettering facilitates the
initial learning of equipment, and facilitates the efficiency of
operating occasionally used equipment.

Current GSA Guideline



1) Large lettering and the use of high contrast colors facilitates
readability. Light gray on slightly darker gray, and other similar
stylish but low contrast combinations should be avoided.

2) Lettering which utilizes most of the key top surface facilitates

3) All keys could be made recappable. This would allow the use of
special keytop kits for visually impaired persons that could
incorporate extra large, high contrast letters, colors, and/or symbols
to facilitate key identification. These could be either custom key
caps or key caps with removable clear plastic lids into which special
legends could be placed. This would be particularly applicable for
dedicated workstations.

4) Sticky tape with unique symbols to identify the various keys,
either on or near the key, could be employed, but is less desirable
unless permanent.

5) Larger, easily readable lettering improves the learning process
and efficiency of occasionally-used equipment for nonimpaired users as




Design Considerations for Individuals
Who Are Blind (B)

Blind individuals have their primary difficulties with the output
display, although newer display-based input systems (e.g., mice,
touchscreens) may also pose problems. The primary solution strategies
involve providing a mechanism to connect alternate display or display
translator devices to the computer, and providing alternatives to
display-based input.
Item B1: Display Data Available at External Connection Point -- and
through System


Blind individuals (and those with severe visual impairments) must use
special alternate displays (voice, Braille, tactile, etc.) to view the
information normally displayed visually. In order for them to use
these alternate displays, it is necessary that these special displays
have access to the contents of the computer's normal display screen.
When the blind individual owns or controls the computer (and can
modify it, insert cards, etc.), access to the screen's contents can be
provided via the internal bus or memory access.
For computers that are shared or public, access must be via an
externally available connection, since the user often is not able to
open or physically modify the computer.



a) Visually displayed information should be available at an external
connection point (standard or special port), preferably in an industry
or company standard format. This information should be provided in
one of the following formats (listed in order of preference): a
description of the information on the display, a character listing
(for character-based screen displays), or a bit image.

b) If an operating system supports multi-tasking, this display
information should also be available to adaptive programs running in
the computer.

PRIORITY: 1 - Access to display data is required by blind individuals
in order to access and use the computer.

Current GSA Guideline

"Access to Screen Memory for Text. The capability to access screen
memory is necessary to support the speech and/or tactile braille
output requirement of many blind users. Currently, blind users are
able to select and review the spoken or braille equivalent of text
from any portion of the screen while using standard application
software. The access to the contents of the screen must continue to
provide third party vendors the ability to direct it to an internal
speech chip, a speech synthesizer on a serial or parallel port, or a
braille display device.

Access to Screen Memory for Graphics. Information that is presented
graphically also needs to be accessed from screen memory in such a
manner that as software sophistication improves, it may eventually be
interpreted into spoken output." (Current GSA - Initial Guidelines,
October, 1987)


1) This is the most important and highest need area for blind
individuals' accessing newer "graphics-oriented" computers. Without
this capability, they cannot use the computer.

2) A bit image dump would minimally satisfy this item, but it would
be much more difficult for an adaptive aid (access system) to
interpret than a properly designed display description format. (See
Note 7)

3) The existing "video output" on most computers does provide the
display image in a continuous fashion on an external connector. This
should (barely) fulfill recommendation (a) until more suitable
solutions can be implemented.

4) Documenting procedures to access the display memory or providing
a system call that would provide a copy of the display memory would
satisfy recommendation (b). Again, access to a description of the
screen is far superior to a bit image.

5) The system might provide a description of the screen contents on
command, or a mode might be invoked where all information that is sent
to the display processor (software or hardware) is also sent to an
external port (or adaptive software running in the background).

6) The external connector could be a standard parallel, serial
(quite slow), or other I/O port.

7) At the present time (early 1988), an appropriate screen
description format does not exist, nor do special adaptive aids
capable of handling this type of input (although several are now being
explored in research).

8) Standardization of software-based screen drawing routines would
allow third-party software to intercept these calls and obtain the
information before it got to the screen.

9) The goal should be to allow information to be intercepted before
it gets to the image creation phase, so that it can be more easily
translated into a form usable by the visually impaired and blind
Item B2: Alternative to Eye-Hand Coordination Input Devices Where


Blind individuals cannot use an input device (such as a mouse,
trackball or touchscreen) which requires constant eye-hand
coordination and visual feedback.


+ Blind individuals cannot use a mouse or trackball, because they
cannot monitor the mouse cursor's continually changing position in
relation to the image on the screen.

+ Blind individuals have difficulty in precisely locating areas
spatially on touchscreens.


If a computer has a standard input system that requires continual
visual feedback to operate (e.g., mouse, touchscreen), the computer
would preferably have an alternative means or mode for achieving as
many of the functions as possible. This alternative means or mode
should be available at any time, and should not require continual
visual feedback.

PRIORITY: 1 - Needed for blind individuals to be able to operate
systems and software which incorporates a mouse or similar pointing

Current GSA Guideline



1) Functions and commands (e.g., menu selections and dialog box
responses) that are also achievable from the keyboard as keystrokes
would satisfy this requirement. This would be the fastest access
technique for blind individuals, and would also facilitate use by
persons with physical disabilities.

2) It is recognized that some activities, such as free-hand
sketching, cannot be easily done other than with a mouse or other
pointing device requiring eye-hand coordination.

3) It is probably impossible to solve this problem entirely (see
Note 2). It is a problem, however, that can be largely eliminated
through maximizing the options for computer operation from the
keyboard (including keyboard equivalents for pointing functions).

4) The existence of macro programs that allow keyboard commands to
initiate pre-stored mouse and keyboard actions can partially but not
completely address this problem.
Item B3: Nonvisual Indication of Toggle Keys' State


Blind individuals cannot determine the state of keyboard (and other)
toggle switches which provide only visual feedback as to their status.


+ Blind individuals do not normally press toggle keys without
knowing it, but when they do, they need a mechanism for determining
status of any toggle key that does not physically lock down (Num Lock,
Caps Lock, Scroll Lock, Insert, Delete, etc.).

+ Not all software provides toggle key status on the screen
(including MS-DOS and some applications). (Software that does provide
toggle key status on the screen can be interrogated by the blind
individual's screen reading software.)

+ Some applications that present toggle key status on the screen
incorrectly report the actual state of the toggle keys as represented
by keyboard indicators.


A non-visual indication of the toggle keys' state should be provided
or available on request.

PRIORITY: 3 - Blind individuals normally don't hit toggle keys
without knowing it, but when they do, they need some mechanism for
determining the status.

Current GSA Guideline

"Toggle Keystroke Control. Currently toggle keys are employed which
require visual feedback to know if a key is on or off. This feature
would provide an alternate mode that does not require visual feedback
to know the status of any toggle key."


1) If status is presented on the microcomputer's standard display,
it is considered accessible, since the screen contents must already be
accessible to the blind user.

2) A system that would provide distinct lock and unlock tones when
toggle keys are activated would satisfy this requirement, even if the
same pair of tones was used for all toggle keys.

3) A command from the keyboard that would cause the system to check
the status of each of the toggle keys and present a unique audible
signal to indicate the status of each key would also meet this need.

4) Some programs on MS-DOS machines get out of sync with the system
toggle status (and keyboard indicators), creating problems. These
software packages, however, usually have an on-screen display of
toggle key status that can be viewed by the blind user.

5) There is some question as to the need for this feature to be
provided within the standard system software or hardware. For a blind
person to use the computer, he/she would need some type of screen
interpretation device (Braille, speech, etc.). Such systems already
have built into them methods for determining the status of toggle key
switches. As totally external alternate display systems are
developed, however, this feature will need to be incorporated into the
standard system unless the toggle key information would somehow be
made available externally to the adaptive system.

6) If all toggle key have bright visual indicators on them, then a
small battery operated light probe can be used by the blind individual
to check the status of the keys.

7) Design rules for software developers should include a statement
requesting that they use (and/or update) the system status flags so
that they agree with the program's use of them.

8) The use of toggle keys that can be directly sensed by blind users
would eliminate this problem. Examples include rocker switches or
double-acting (pop-up, lock-down) keys.
Item B4: Nonvisual Key Labelling


Blind individuals have difficulty in identifying some of the keys on
keyboards and keypads, as well as locating "home" keys on keyboards
and keypads.




Keyboards/keypads should have tactilely discernible key edges (e.g.,
no flat membrane keyboards without ridges).

A distinct tactile marking should be provided on the home keys for
keyboards and keypads.

Optional or built-in nonvisual key labelling should be provided or

PRIORITY: 3 - Most important when an individual is learning a
keyboard or trying to locate a seldom-used key.

Current GSA Guideline

"Keyboard Orientation Aids. There are several different keyboards
available for current personal computers. To orient a visually
impaired user to a particular keyboard, a set of tactile overlays
should be available to identify the most important keys (e.g. ESC,
ENTER, CTRL, ALT, and several key letters and numbers). The tactile
overlays might be keycap replacements or transparent sticky tape with
unique symbols to identify the various keys.


1) Placing control keys near tactile landmarks, such as along the
edges of the keyboard (not burying them in the center) allows tactile
markers to be placed very discretely and stylishly alongside controls.
Symbols may be embossed in the case in the same color, next to the
control key, so that the user can touch and identify it.

2) Use of spatial grouping of keys (such as the cursor keys arranged
in a T) provides natural tactile landmarks. Using small groups of
keys that are separated from the other keys also facilitates key
finding (e.g., second key in the second group).

3) Maintaining a "standard keyboard" layout is very helpful, and
allows blind individuals to switch between computers or systems
without confusion.

4) Overlays can be used that put tactile labels alongside the keys
located around the edges of the keyboard. A separate tactile
(including Braille) map of the keyboard could also be used.

5) A common approach for providing tactile markings of the home keys
is to put nibs centered on or at the front edge of the F and J or D
and K keys on the keyboard, and on the 5 key on a keypad.

6) Flat membrane keypads or buttons should use ridges around keys, a
bump (or depression) in the center of the keys, or a plastic guard
(with holes for each key) to make the keys tactilely locatable. This
is very important even if the keys are only labeled visually --
especially for control buttons on peripheral devices (like a printer)
where the function of the keys can be easily memorized if they can be
tactilely located on the control panel.

7) If the computer has voice output capability, a command could
temporarily disable the keyboard but cause keys to be spoken when they
are pressed, to allow an individual to locate a particular key




Design Considerations for Individuals
Who Are Hearing Impaired or Deaf (H)


Hearing impaired and deaf individuals currently have little difficulty
in using computers. Visual redundancy of clicks and tones and other
auditory output would address most of the problems in this area. The
primary concern is ensuring that future voice output information is
provided in a redundant form that hearing impaired or deaf individuals
can also understand.
Item H1: All Audible Output Also Provided in Visual Form


Individuals who are deaf cannot receive any information (tones, voice,
etc.) presented in audible form.


+ Individuals who are deaf cannot hear beeps or other tones that
are intended to alert them to problems or system status.

+ Individuals who are deaf cannot hear spoken output from a

+ Individuals who are deaf cannot hear the disk drives and cannot
tell when they are in operation if no visual indicators are provided.


All information presented in auditory form which is required for
system operation and error detection should also be provided or
available redundantly in an appropriate visual form.

PRIORITY: 1 - Where the auditory information is required for system
operation, deaf individuals would be unable to operate the device if
the information is not also provided in visual form.

Current GSA Guideline

"Information Redundancy. Currently, several programs use the speaker
to beep warnings or errors to the user. Some programs do not have the
capability to present the warning visually to the hearing impaired
user. This feature would allow the user to have information
redundancy by presenting a visual equivalent of the beep on the
monitor. This might be accomplished by either a manual screen
indicator (i.e., the user would have to indicate that he has seen the
warning indicator by entering a key sequence to remove the indicator
from the screen) or an automatic screen indicator (i.e., the warning
would be presented for a period of time and then removed


1) Warning beeps and tones could be accompanied by a visual
indicator, or flicker on the screen.

2) Synthesized or digitized speech messages could be redundantly
presented in visual form.

3) Provide as a part of the operating system a "feedback
preference" setting or "hearing impaired user" flag that would be set
by any user who wanted visual support to accompany auditory output.
The operating system and application programs could then provide full
visual redundancy for all audio output when the flag is set. Suggested
settings for a "Feedback Preference" setting might be:

a) Sound is okay.
b) Use visual cues.
c) Use locking visual cues.

This last setting would be used by individuals who do not look at
the screen while typing, and who might otherwise miss cues that are
only displayed for a moment.
Application programs could check for the feedback preference
setting and provide visual cues to accompany auditory cues when they
are so requested. Programs with speech output could provide what
amounts to a caption on the screen, to accompany or replace the speech
output when the preference flag is set.

In addition to being useful to people who are deaf, this feedback
preference capability would be useful in noisy environments, where
beeps might be missed, and in quiet environments such as libraries
where the sound level may be set very low or off, to avoid disturbing

4) Training materials (videotapes, audiovisual computer
presentations, etc.) would not normally be considered as "required for
operation" and would be exempt (although subtitling would be

5) In the future, education, training and other software may include
speech to accompany on-screen activity. This may be more text than
would normally be displayed on screen. Operating systems could
support a sort of built-in closed captioning capability that could
then be used by application programs. A deaf individual could enable
the captioning feature by setting the "feedback preference" or a
"hearing impaired user" flag. The closed captioning feature would
then display text on the screen (sent by the application program) to
accompany the spoken text.

This feature would also facilitate use of equipment by
individuals for whom English is a second language, individuals who
have poor language skills, or in a noisy environment.

6) The presence of a headphone jack provides the opportunity to plug
in a small LED that would provide a visual flicker whenever sound was
emitted from the speaker. This would be sufficient to indicate that a
beep had occurred, but insufficient to distinguish the type of beep or
speech. A microphone placed next to the speaker might provide a
substitute for a headphone jack, except that it is likely to pick up
loud noises in the environment (e.g., setting down a book hard), which
might give false flashes.

7) A small LED might be wired in parallel with the speaker to
provide visual feedback of auditory activity.

8) If different tones are used to convey different messages, they
should be accompanied by different visual signals.
Item H2: Audio Output Should be Adjustable as well as being Available
in a clear form for Amplification


Individuals with hearing impairments have difficulty hearing auditory
output from computers, or cannot turn up volume sufficiently due to
environmental constraints.


+ Individuals who are hard of hearing (not deaf) have difficulty
hearing beeps that indicate errors when typing or issuing commands.

+ Individuals who have hearing impairments are unable to turn the
volume up sufficiently in some environments, such as libraries (not
allowed) or a noisy environment (not enough volume).


a) Sound volume should be adjustable and/or reasonably loud.

b) It should also be easily available in a clear form for

PRIORITY: 1 - (If all auditory information is provided in a redundant
visual form [see H1], the importance of Item H2 is much less.)

Current GSA Guideline

"Auditory Output Capability. . . . The volume should be adjustable by
the user and a headset jack should be available."


1) An adjustable and fairly loud volume is particularly helpful to
aging individuals and others with mild hearing impairments who do not
normally carry or use hearing aids or other sound amplification
devices. Volume that is "reasonable" for a particular computer is a
function of the unit's size, usual operating environment (quiet/noisy)
and type of sound. Beeping tones that have a strong component below
750 hertz are easier for many hearing impaired persons to hear.

2) Placement of the sound source near a quiet (no loud fan nearby)
and user-accessible location on the equipment (such as an edge), or
the provision of an audio jack, would satisfy part (b) of this
recommendation. Hearing impaired individuals could then carry a pair
of headphones or headphones plus a small, $25 battery-operated
microphone and amplifier to provide the necessary sound levels. This
allows the user to select an amplifier that matches the particular
volume level they need. (The jack or portable microphone could also
drive an inductive neckring, which would allow the sound to be
directly coupled to the user's hearing aid.)

3) The headphone jack provides the greatest privacy, which is
important for "quiet" environments (such as a library) when (if) text-
to-speech synthesis becomes native in the workstation, or when
applications utilize speech output as a standard user interface
(especially in a multiple workstation environment, where it may be
difficult to determine which computer the speech is coming from).




Design Considerations For Individuals
Who Have Seizure Disorders (S)

Item S1: Displays and Software Avoid Some Refresh and Update


Individuals with seizure sensitivities may be affected by cursor or
display update frequencies, increasing the chance of a seizure while
working on or near a display screen.



Displays should avoid whenever possible refresh or update flicker or
flashing frequencies which are most likely to trigger seizure

PRIORITY: 1 - Important to health and physical safety of individuals
with seizure sensitivities.

Current GSA Guideline

"Cursor Presentation. Where cursors or other indicators on the screen
blink, the end user should be able to adjust the blink rate. This
feature accommodates persons with seizure disorders who may be
sensitive to certain frequencies of flashing light."


1) This is an area of potential concern which has only been
partially defined and quantified.

2) Somewhere between 1 in 25,000 and 1 in 10,000 are affected by
photosensitive epilepsy (total: 25,000-100,000 people) (Cakir, Hart, &
Stewart, 1980, Visual Display Terminals, pp. 219-220, John Wiley &

3) The flash rates most likely to induce convulsions in
photosensitive epilepsy have been found to be between 10 and 25 hertz,
with a peak around 15-20 hertz.

4) This chart illustrates the relative sensitivity of individuals to
different frequencies: it shows the relative sensitivity of
photosensitive patients in whom a photoconvulsive response was
elicited by 2 second trains of flashes, expressed as a function of the
flash frequency. Solid dots = response with eyes open; open dots =
eyes closed (Jeavons, P.M., and Harding, G.F.A. [1975] Photosensitive
epilepsy. London: Heinemann.)

Put chart here:
four inches of space needed





5) Sensitivity to frequencies below 8 hertz is uncommon, so that in
connection with VDTs, a 5 hertz or lower blinking cursor is unlikely
to prove epileptogenic (Sakir, Hart, & Stewart).
6) There is a good deal of evidence to suggest that combined
presence of pattern and flicker may extend the sensitivity range. The
results from one investigation, for example, showed that while the
mean sensitivity range for diffuse stimulation was 11-13 hertz, the
range was increased to 10-43 hertz with patterned stimulation. This
difference confirms a conclusion that has been drawn by most
researchers in the field, that pattern stimulation is more
epileptogenic than diffuse stimulation. It has also been found that
many photosensitive epileptics are not only sensitive to flicker but
also to stationary striped patterns, and that by vibrating patterns
the incidence of pattern sensitivity is doubled (Sakir, Hart, &

7) Stimulation in the 30 hertz range may occur in some fast phosphor
interlaced displays. Stimulation in the 10-20 hertz range can occur
with systems that blank and redraw the screen rapidly, such as when
scrolling through a display or flashing very quickly across a series
of images. This can also happen when a computer program executes a
keyboard macro within an application program. The flash rate is not
necessarily uniform, but can be quite rapid on a fast computer.
Poorly executed animation that produces a flickering image in this
range might also cause a problem.

8) A seizure-sensitive individual need not necessarily be working
directly at a piece of equipment in order to be affected by the
device, although they would need to be in visual contact with it.




Design Considerations that Would Facilitate
Development of Computer Access Devices
by Third-Party Manufacturers (M)
Item M1: Manuals Available in Electronic Form


Blind individuals cannot read printed text, and physically impaired
individuals cannot handle printed documentation.



Make manuals and other important documentation available in electronic

PRIORITY: 2 - Facilitates learning of systems and occasional
reference. Sometimes needed for daily operation.

RECOMMENDED EXCEPTIONS: Software manuals and manuals sold separately
from physical equipment might be excepted (due to software piracy

Current GSA Guideline

"Documentation. The vendor will maintain a copy of all current user
documentation on a computer, and will be responsive in supplying
copies of this documentation in an ASCII format suitable for computer-
based auditory review or brailling."


1) Availability of manuals from third-parties (Library of Congress,
American Printing House for the Blind, etc.) should fulfill this

2) For documentation to be completely accessible, all information
presented graphically should also be presented in text.

3) When full manuals are not available (and even when they are),
command or reference summaries in electronic form or on-line are very

4) It is recognized that there is a problem in providing electronic
copies of software manuals and manuals that are not provided along
with a piece of hardware, since provision of electronic versions of
software manuals facilitates software piracy. Manuals that are
normally included directly with the hardware, however, could be made
available in electronic form with little or no risk to the
Item M2: Speech Output Compatible


Individuals who are severely visually impaired or blind often use
screen access programs which read the contents of the screen back to
the individual, using a speech synthesizer. These special access
programs need some way to access speech synthesis capability.
Speech impaired individuals and deaf individuals who are also speech
impaired could also use computers which have speech output capability
for communication (either in person or over the telephone).



A speech output capability would preferably be built in or available
via connection of a speech synthesizer to an output port.

PRIORITY: 2-4 - The ability to at least connect a voice synthesizer
is a high priority. Having the speech synthesis built into the
computer is very useful, but a lower priority, as long as an external
synthesizer can be connected.

Current GSA Guideline

"Auditory Output Capability. The auditory output capability on
current personal computers is sufficient to beep and play music. Some
users with disabilities, however, may require speech capability. For
speech to be generated on today's computers, a speech synthesizer is
required. The capability to support a speech synthesizer must
continue to be available in future generations of computers or this
capability must be internalized through an upgrade of the computer's
internal speaker. Regardless of the methodology chosen, the volume
should be adjustable by the user and a headset jack should also be


1) The availability of an (unused) standard RS232 serial port on a
computer is sufficient to guarantee that a synthesizer is available
that can be used with the computer.

2) The ability of a computer to generate its own synthesized speech
is a function of the quality of the speaker, the audio amplifier, and
the sound generation system. Although it is possible to generate
speech output from a speaker connected to a bus data line, high
quality speech generally requires a sound synthesizer chip, preferably
one capable of generating sine wave output.

3) A standard add-in board that could add voice would be useful.
Built-in voice would be better, especially in portable computers which
have only one serial port.
Item M3: Special Display Window Which Can Stay Visible (on top)


Some operating systems do not provide a mechanism that allows programs
running in the background (or under multi-tasking) to provide visual
information continuously to the user. This prevents the use of low-
cost software-based input systems, which require continuous visual
selection or feedback.


Special adaptive access (input) programs put a keyboard image on the
screen, and the user "types" by using a cursor controlled by head
movements, eye gaze, single switch scanning, etc. This window must be
able to always remain "on top." If this window "keyboard" simulated
both the keyboard and mouse movements for the user, and the window
were to disappear (behind another window), the user would have no
means to bring it forward, and would be locked out (since they would
no longer have access to their "keyboard" or "mouse").


Windowing environments would preferably have the ability to open and
maintain special windows which can remain always fully visible (for
use by special input routines).

PRIORITY: 4 - This feature can greatly reduce the cost of providing
access to a computer by allowing use of special adaptive software in
place of a separate alternate access system.

Current GSA Guideline



1) The special window should cover only part of the screen, and be
movable and shrinkable, to allow the user to move it around to view
different parts of the screen as required.

2) This feature can greatly reduce the cost of providing access to a
computer by allowing the use of special adaptive software running in
the computer instead of a separate hardware alternate access system.
Item M4: Connection Point for Switches or Transducers "


Many computers have no provision for connecting external switches
needed for some adaptive access programs.


An eyeblink-operated scanning program needs a way to connect the
eyeblink switch to the computer. A sip-and-puff Morse code input
program needs a way to connect two switches.


Systems would preferably provide a standard way of connecting at least
two momentary contact (SPST) input switches.

PRIORITY: 4 - This feature lowers the cost of adapting workstation
computers by allowing easy connection of switches and use of internal
access software.

Current GSA Guideline



1) Connection point for switches could be implemented as dedicated
pins on an already existing connector, or optional use of seldom used
signal lines already existing on a connector.

2) The ability to connect analog transducers as well as binary
switches is desirable, since it increases the input options for
special software.

3) Arrays of up to 128 switches (8 x 16) are currently used as
special inputs for adaptive software.
Item M5: Method for Distinguishing Macro Input from Keyboard Input"


Some software programs discard certain keystrokes that show up in
typing buffers, interfering with the user of special "macro"-based
acceleration programs.


This problem usually arises when application software throws away
strings of multiple backspace and other cursor movement characters.
This is done in programs like Microsoft Word to avoid the overshoot
problems such as are encountered in Lotus 1-2-3 when the back arrow
key is held down until the desired position is reached (or until the
desired deletions are completed). This tendency to throw away
multiple back arrow or back space keystrokes when they rapidly appear,
interferes with macros used by disabled individuals as well as some
input acceleration programs such as abbreviation expansion (which must
erase the abbreviation before printing the expansion).


Operating systems would preferably provide a means for distinguishing
between typed, auto-repeat, and macro-generated "keystrokes" so that
they can be treated differently by the operating systems and
application software.

PRIORITY: 4 - The presence of this feature allows the use of special
software which increases the input efficiency of physically disabled
individuals, but is not required for their access to computers.

Current GSA Guideline



Item M6: Keyguard or Keyguard Mounting Provision


Individuals with poor use of hands, or using mouthstick, headstick,
etc., may require the use of a keyguard (a plate with holes over each
key) in order to accurately use a standard keyboard. Third-party
manufacturers make keyguards, but have difficulty mounting them to



Provision would preferably be made in the design of the keyboard to
facilitate keyguard mounting. In addition, the keyguard could be made
available directly from the manufacturer.

PRIORITY: 5 - Would increase the ease and lower the cost for third-
party manufacturers to develop keyguards for computers.

Current GSA Guideline

"Keyboard Orientation Aids. . . . To assist a motor disabled user, a
keyguard should be available to ensure that the correct keys are
located and depressed."


1) The largest problem is with shared computers, where the keyguard
must be removed and replaced. Velcro or posi-lock fasteners are
currently being used in these applications.

2) Keyguard mounting might be accomplished by incorporating a groove
in the side of the keyboard, with perhaps a dimple in the groove where
it would not show. The keyguards could then slide into place.

3) Sculptured keyboards complicate the fabrication of keyguards.

4) With portable computers, it would be useful to have sufficient
clearance above the keyboard so that a keyguard could remain in place
when the computer was closed.