Often, accessibility efforts focus 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, other aspects of the computer’s design are of little importance.
Some users have conditions that result in weakness or poor motor control. Some have use of just one hand or reduced range of motion or reach. Hardware design strategies for providing greater access include the following:
1.Eject media a sufficient distance for grasping.
Ejecting 0.5 to 0.75 inch or more is helpful for those with reduced hand functions.
2.Sculpt or bevel device entry slots.
This assists in 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. CDs should seat themselves properly when dropped into trays (that is, no fine positioning is required from the user). The CD should also be easy to remove from the tray (that is, slots at the sides of the tray allow for placing a finger under the disc to lift it out).
3.Make latches operable with one hand.
This allows those who do not have use of limbs or who use assistive pointing devices to operate latches.
4.Minimize the force required for inserting and retrieving media.
This assists those with reduced strength and grasp capabilities. A maximum force of 2 Newtons is advised, but it is preferable for the mechanism to “suck” the disk in for insertion and to not require a force of more than 2 Newtons for pulling it out of the slot.
5.Ensure that media stands up to rough handling, and use caddies for media that do not.
This allows individuals with poor motor control to safely handle all media without inflicting irreversible damage.
6.Provide error flags for misinserted media, especially CDs.
When it is not possible to block misinserted media (see item 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 be an asset for users with visual impairments and as well as for novice users.
7.Ensure that devices do not generate electromagnetic or radio frequency (RF) fields that would affect 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:
8.Use media misinsertion blocking.
Blocking assists all users as a memory aid, but it especially helps those with low vision or cognitive impairments who might forget or misinterpret how to insert media.
9.Offer components that allow for use of alternative input devices.
This assists those who use alternative input or output devices because of the nature of their reduced ability.
10.Provide adjustable height, swivel, and so on where appropriate.
Adjustable components assist those who do not have a full range of movement; displays and input devices can be oriented toward the user.
11.Minimize operation noise levels.
In general, quieter components (fans, disk drives, and so on) are easier to use for users with neural hearing loss or hearing aids.
12.Eliminate hard edges or sharp corners that could cause injury or inhibit correct device placement.
Softening component edges assists those with reduced motor control, minimizing the potential for injury.
13.Manufacture outer surfaces using only hypoallergenic materials.
Chromium and nickel are known to cause allergic reactions in some users and should therefore be avoided in any part that could come into contact with users’ skin during normal use.