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Photograph of a computerComputer Hardware

Computer hardware is the physical part of a computer, including the digital circuitry, as distinguished from the computer software that executes within the hardware.

Although there are many adaptations that can be made to computer hardware so that those with disabilities can access computers more readily, designers of computer hardware should be aware of accessibility features that can be incorporated in the initital design and development stages.


Most computer hardware is not seen by users as it is embedded within the devices. A typical personal computer, the computer hardware familiar to most people, consists of a case or chassis and the following parts:

In addition, hardware devices can include external hardware components. The following are either standard or very common peripheral devices identified with a computer system:

Input peripherals Photograph of a webcam and mouse

Output peripherals

Problems encountered by disabled people and the ageing population using computer hardware

Blind and Partially Sighted

Blind and partially sighted users often have problems with reading the display and seeing other visual details on the screen. The size of the screen, screen resolution, availability of colours, fonts and font sizes will all have an impact on how blind and partially sighted users access a computer.

Blind and partially sighted computer users may have difficulties using input devices such as a mouse, due to the size and movement of the cursor and the difficulty in interpreting spatial relationships, such as layout. The option to use keyboard input instead of a pointing device is an essential feature for blind and partially sighted users.

Any textual documentaton that comes with computer hardware for installation or instructional purposes will be problematic for blind and partially sighted users.

Hearing impaired

Sound is often used to alert the computer user of an error, to signify task completion or that an input is required.  For those who cannot hear the sounds, alternatives may be required. The increasing use of multi-media output means that more consideration should be given to the needs of hearing impaired users.

Physically impaired

Physically impaired users often have difficulty in using input devices or in handling storage media. Providing a means to connect an alternative keyboard would often help people with a severe physical impairment. However, connecting peripheral hardware devices to a computer may also cause problems if connection terminals are not within easy reach of the user.

Cognitively impaired

People who have a learning disability such as dyslexia, may find difficulty in reading and deciphering text both on a keyboard and on a screen.

Some users with cognitive impairments may struggle with the concept of what a keyboard or mouse is for. For example, a user may be an incredibly agile and fast mouse user, but has no interest or desire to use a keyboard. In this case a number of hardware or software solutions may help to overcome these difficulties.

People with the specific condition called ‘photo-sensitive epilepsy’ may find that moving or flickering light can cause problems, and this can include computer screens. Only a minority of people with epilepsy are in fact photo-sensitive. For many others, the problems they experience while using a computer are not due to the movement, or “flicker”, of the screen image but rather to other causes such as eye strain and general stress.

Overly complicated installation or instruction manuals can also prove to be a challenge for some people with cognitive impairments.

Photograph of an elderly lady using a computerAgeing population

Elderly people can experience a range of the problems mentioned above due to reduced physical, sensory or cognitive abilities that come with advancing age. It is also known that because some elderly people can have trouble reading and are slower to understand and learn new things they tend to view computers as complex machines that are fast and hard to understand. They have a natural tendency to distrust computers, and a certain reluctance to begin working with them.


Checklist for computer hardware

 

Recommendations

Controls

According to the Nordic Cooperation on Disability (1998) operation of a control should not:

The Design Considerations Task Force of the Industry/Government Cooperative Initiative on Computer Accessibility (1988) states that push button controls should:

Keyboards and keypads

Basic ergonomic features
Localisation of keys
Identification of keys
Activating keys

According to the Nordic Cooperation on Disability (1998) the power to press a key should be:

Pointing devices

Drives and removable media

Displays

Colour and contrast

Photograph of jack sockets for a microphone and headphonesAudio output

Photograph of a USB portExternal connections

Peripheral devices

Printers

Instruction manuals / Documentation

Manufacturers should provide access to information and documentation including user guides, installation guides and product support communications.

 

Standards
  • 36 CFR Part 1194 [Docket No. 2000-01] RIN 3014-AA25 (2000) Electronic and information technology accessibility standards - Section 508
  • EG 202 116 (2002) Human Factors (HF); Guidelines for ICT products and services: Design for all
  • ETSI TR 102 068 (2002) Human Factors (HF): Requirements for assistive technology devices in ICT
  • INCITS 154 (1988) Office machines and supplies - Alphanumeric machines - Keyboard arrangement (formerly ANSI X3 154 (1988) (R1999))
  • ISO 9241-4 (1998) Ergonomic requirements for visual display terminals - Part 4: Keyboard requirements
  • ISO 9241-11 (1998) Ergonomic requirements for visual display terminals - Part 11: Guidance on usability
  • ISO 9241-300 Ergonomics of human-system interaction - Part 300: Introduction to electronic visual display requirements
  • ISO 9241-302 Ergonomics of human-system interaction - Part 302: Terminology for electronic visual displays
  • ISO 9241-303 Ergonomics of human-system interaction - Part 303: Requirements for electronic visual displays
  • ISO 9241-304 Ergonomics of human-system interaction - Part 304: User performance test methods
  • ISO 9241-306 Ergonomics of human-system interaction - Part 306: Field assessment methods for electronic visual displays
  • ISO 9241-307 Ergonomics of human-system interaction - Part 307: Analysis and compliance test methods for electronic visual displays
  • ISO 9241-410 (2008) Ergonomics of human-system interaction - Part 410: Design criteria for physical input devices
  • ISO/FDIS 9241-305 Ergonomics of human-system interaction - Part 305: Optical laboratory test methods for electronic visual displays
  • ISO/IEC 10741-1 (1995) Information technology - User-system interfaces - Dialogue interaction - Part 1: Cursor control for text editing
  • ISO/IEC 14755 (1997) Information technology - Input methods to enter characters from the repertoire of ISO/IEC 10646 with a keyboard or other input device
  • ISO/IEC 15411 (1999) Information technology - Segmented keyboard layouts
  • ISO/IEC 15412 (1999) Information technology - Portable keyboard layouts
  • Nordic guidelines for computer accessibility (1998) 2nd edition
  • UNE 139801 (2003) Computer applications for people with disabilities. Computer accessibility requirements. Hardware

Further information

Acknowledgements

 



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