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PDAs are a reasonably new an d emerging technology that has seen a fair bit of growth over the last few years. Their use as an educational tool is being widely explored. Their employment as a tool to 'include' a variety of learners has also begun.
The accessibility of a PDA can be viewed from two perspectives:
These two possible strands of a PDAs functionality are not mutually exclusive since it is necessary that a PDA is functionally accessible to be of use as an assistive technology.
Both the manufactures and developers of PDA handhelds, operating systems and their software have not generally considered the accessibility of their products. The development of PDAs has been so fast since their evolution beyond PIM systems and little analysis has been made of the functionality of some PDAs for disabled people.
Though much advancement has been made on the accessibility of desktop computers with increasing amounts of assistive technology, the swift , often monthly development of new PDA models has meant little has been learnt from retrospective analysis. However one notable advancement in the usability of a PDA is the implemen tation of a Jog dial by Sony and others onto the side of their handhelds.
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For those with a visual impairment, PDAs can be quite inaccessible. The small screens, often with poor resolution, can make accessing the graphical user interface difficult.
The Palm based PDAs can be given a better colour contrasting graphical interface using the Butterfly application. Basic magnification can be achieved using TealLens but this is not the best possible solution as it can be only used as an "inactive screen shot" magnifier. Only small font size increases can be achieved making the text a maximum of 14 points in size.
In Pocket PC based PDAs the graphical interface can be given a better contrasting colour scheme though this is not yet achievable in the Pocket Word application. No screen magnification is available, although it would be possible to design a software program to achieve this function.
The main problem for the Pocket PC user is the small size of the text that can be enlarged in size up to 20 points using the zoom function in Pocket Word and Excel. However the integration of this enlarged text capacity is dependent upon the software designers including it in there application.
True Text-to-speech (where speech is synthesised dynamically by a speech engine using the processing power of the PDA) is only possible using PDAs running the Pocket PC operating system due to its higher processing power. This could be used to provide equal access to the text for those with problems reading the smaller print.
A PDA screen reader (a text-to-speech software program that makes all user interface features accessible, e.g. navigation) is only available using the Pac Mate, which has a specially adapted version of the Pocket PC operating system and an extended battery and keyboard.
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For those with hearing impairments, PDAs do not present many inaccessibility problems. Though if pre-lingually deaf, users will also face the same problems of inaccessibility that users with speech and language difficulties encounter with complex language issues.
The major accessibility difficulty is audible alerts, which are used for alarms, and users alerts (such as for errors). Only some Palm models have vibrating alert option, as other PDAs if fitted with vibrating alerts would simply wobble of the end of a table because they are too big. Nokia 9210 phones with PDA functions do not have the vibrate function for that reason.
Both operating systems have the ability to customise the tone and pitch of the audible alerts through third party software adjustments.
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For those with a manual dexterity problems the main difficulty encountered when using a PDA is a touch screen interface that is usually triggered by a stylus. Stylus control is one of the key features of modern PDAs, it allows a flexible 'reactive user interface', Good finger dexterity is required, as small movements are required to use the onscreen controls. Interactions that require larger hand and wrist movements to move the stylus greater distances than are possible with the fingers are more likely to aggravate RSI or other dexterity difficulties.
Since most PDAs have IR ports it would be possible to use any ergonomic keyboard (or other input device) that also has an IR port if appropriate software drivers were available. Sadly many companies have not researched this method of input, although switch access and certain types of keyboard access are available.
Currently peripheral generic keyboard control and data input remains the most appropriate interface interaction method. Keyboards of a near full size are available for most models of PDA and alternative keyboard mapping is available for formats such as DVORAK. The simpler interface of the Palm operating system currently provides the best support for external keyboard use, especially when combined with a virtual onscreen mouse (PointerHack).
The integration of a Jog Dial (a rocking wheel for scrolling and a push action for object selection) for Sony Palm PDAs and some Pocket PC PDAs provides better control of the operating function though manual control. Although the position can be difficult for left handed users.
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The small screen of a PDA means that developers appear to have developed a specific type of language suited to a limited physical space. There are often abbreviations and short language terms as well as PDA specific language. Users with language comprehension difficulties would benefit from a glossary of PDA terms that was easily accessed rather than having to use web-based versions or checking in manuals.
Dyslexic users have the problems of high-resolution screens with few background or font type modifications available. Menus on the Pocket PCs are often long and cramped and reading without sufficient white space becomes an issue. However, as has been mentioned under visual impairment, some PDAs offer text to speech and the Palm OS can be used with a program that changes the background colour.
Augmentative and Alternative Communication devices are now available as Pocket PC versions and these can be very helpful for those who wish to communicate using symbol or graphical based systems.
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PDAs are small devices that do not weigh much in comparison to a large textbook. Though with the addition of a peripheral keyboard and possible mains charger a bag or carry case would be necessary.
Mounting brackets and holders are available for PDAs that were originally designed for use in a vehicle. However these could be adapted for use on a flat surface (such as a table) or used for fixing to a wheelchair.
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