Manipulation and Physical Design

Often the focus of accessibility efforts is on the input or display components of a computer. However, many of the physical design characteristics of the computer are equally important. For example, if the person is unable to operate the latches to open a portable computer, the other aspects of the computer's design are of little practical importance.

Some users have conditions that result in weakness or poor movement control. Some have use of just one hand. Some have reduced range of motion or reach.

Hardware design strategies for providing greater access to the physical design of products include the following:

Eject media a sufficient distance for grasping.
Ejecting 0.5 to 0.75 inch or more is helpful for those with reduced hand functions.
Sculpt or bevel entry slots and so on (including compact disc trays).
Assists guiding the disk into the slot for those with reduced motor control. This also gives a tactile indicator, which helps those with low vision locate the slot. Compact discs should seat themselves properly if dropped into trays. (That is, no fine positioning is required from the user.) The disc should also be easy to grab from the tray (that is, allow slots at the sides of the tray for placing a finger under the disc to lift it out).
Make latches operable with one hand.
Allows those who do not have use of limbs or those who use assistive pointing devices to operate the latch.
Keep force required for operation to a minimum (that is, less than 2 Newtons) for inserting and retrieving media.
Assists those with reduced strength and grasp capability. A maximum force of 2 Newtons is advised, but it is preferable to have the mechanism "suck" the disk in for insertion and not require a force of over 2 Newtons for pulling it out of the slot.
Ensure that media takes rough handling (use caddies for media that does not).
Allows individuals with poor motor control to safely handle the media.
Provide error flags for misinserted media (especially compact discs).
When it is not possible to block misinserted media (see description 8 below), the hardware could contain a disk-present detector to warn the user that a disk has been inserted but is unreadable because it is upside-down (and not just in an unreadable format). This would greatly assist users with visual impairments and also novice users.
Ensure that devices do not generate electromagnetic or RF fields that would affect users with hearing aids.
Assists those users with hearing aids. Electromagnetic fields can couple with induction pick-ups in hearing aids, causing loud or disturbing noises. RF can affect all hearing aids. There are currently no industry standards for these levels, so reasonable care should be taken and testing is recommended.

The following design practices are fairly standard and also facilitate access and use by users with disabilities:

Use media misinsertion blocking.
Assists all users as a memory aid, but helps especially those with low vision or cognitive impairments who might forget or misinterpret how to insert media (such as upside-down).
Have separate components that allow for use of alternative input devices.
Assists those who use alternative input or output devices because of the nature of their reduced ability.
Provide adjustable height, swivel, and so on where appropriate.
Assists those who do not have a full range of movement — displays and input devices can be oriented toward the user.
Have low noise operation.
In general, quieter components (such as fans, disk drives, and so on) in computers are easier to use for those people with neural hearing loss or those who use hearing aids.
Have no hard edges or corners that could case injury or that could inhibit correct placement.
Assists those with reduced motor control.
Have no material that can cause an allergic reaction.
Chromium and nickel are known to cause allergic reactions in some users and should therefore be avoided in any part that users could contact with their skin during normal use.