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PDAs should ideally fit easily into the average sized hand and be easy to hold. Tactile grips could provide greater support for those with manual dexterity problems.
Ideally PDAs and their peripheral devices should not be too heavy and remain easily portable which does seem to be the aim of most designers. However, at present most add-ons are fiddly to connect and can not be considered very robust. .
People with who have lost some sensitivity in their fingers or have manual dexterity problems and those who are visually impaired would benefit from better designed buttons and switches with clear markings and tactile additions such as those offered on some mobile phones. Buttons should ideally be raised or clearly identifiable (both visually and by feel) and be in ergonomic positions. Some require far too much fiddly scrolling or direction twiddling to produce actions on the screen.
People with visual impairments and those with reading difficulties may find that coping with text on a small PDA can be problematic. Screens should ideally have a good quality resolution, a reasonable colour depth and clear screen lighting. However, as with all computer monitors and text that scrolls down or across a screen it is a question of testing the tools in different environments if possible. A dark area needs a bright screen and a monochrome PDA chosen in a shop may not suit the user when the daylight fades.
Providing good support for hardware buttons to allow those operating PDAs with limited movement (perhaps manual dexterity problems or single handed) would increase a PDAs usability.
Ideally all functions or operations should be available via keyboard commands (if a peripheral keyboard has been added/connected). The hardware (or fixed software screen) buttons should be instinctive and customizable to allow the user to perform all navigational functions and most operational commands without resorting to using a stylus.
People with visual impairments will have problems reading the text and graphics on the display as well as identifying the functions of the hardware buttons. They may benefit from the ability to resize text or magnify graphics and change the colour or contrast of a display. External keyboards with shortcuts for navigation as well as an external magnifying glass may also be necessary. But it has to be accepted that these devices may not be accessible or usable unless they have be especially designed for the purpose for instance the PAC Mate by Freedom Scientific . Pulse Data are also providing a Palm application that connects BrailleNotes to Palm PDAs (via a serial cable) so that a user can show a sighted person what they have been writing in Braille.
People with specific learning difficulties and/or dyslexia may find some of the complex graphical interfaces provided on some PDAs confusing - those trying Pocket PC will find cramped toolbars plus menus with long lists.. All small screens tend to result in a lack of 'white space' and there is usually little chance to choose a favourite font. Once again it may help to resize text or graphics and change the colour or contrast of a display
People with Hearing impairments may not have any difficulties with the GUI interface and operating system. However for those who tend to communicate in sign language and find English difficult, the PDA language may be confusing. There is a type of technological jargon that runs throughout all the websites, manuals and forums and it is with this issue in mind that we have produced a glossary.
People with mobility and dexterity difficulties may not have any problems looking at the GUI interface but when they try to access it with a stylus, small button or keyboard, issues of manipulation may arise. The options for mouse or switch access are limited but remote control, IR and Bluetooth may be the way forward. In fact those with very major mobility and communication difficulties have been using GUI interface communication aids for a long time.
Ideally the GUI should be intuitive and have user-friendly navigation and functionality. Also with a clear readable, uncluttered visual design that can be resized or enlarged. The operating system should support large enough graphics to allow easy viewing and stylus control.
The longer the battery life the better! Most students will be at university or college for up to eight hours a day and will have different usage needs. Some older PDAs used small AA batteries or have back-up batteries but most are now dependent on an AC charger and it can help to choose a model that does not require a cradle for charging.
For those with disabilities who require extras to make their PDAs accessible and usable it is often essential to consider devices that offer:
As has been mentioned the difficulties that tend to arise with this aspect of using a PDA are related to dexterity and being able to slot the PDA into the fitting. Plugging in cables and setting up the synchronisation through the hardware button or software synch program on the computer or PDA can also be fraught with frustrations if things do not go smoothly.
People with hearing impairment would benefit from a vibrating alert to accompany an alarm. Ideally the auditory alarm should have a variable pitch and volume to allow for people with different hearing ranges.
Visual alerts such as a flashing Light Emitting Diode (LED) or flashing display screen would help users with visual and/or hearing difficulties and those who do not wish to disturb others in a library for instance.
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