Apple IIgs #91
The Wonderful World of Universal Access

Revised by Dave Lyons (May 1992)
Written by Don J. Brady, Matt Deatherage, & Ron Lichty (September 1990)

This Technical Note discusses how your applications can be compatible with Universal Access software.

Changes since July 1991: Added caution against reading the keyboard with interrupts disabled.

What's "Universal Access?"

Universal Access is the name given to software components designed to make Apple computers (in this case, the Apple IIgs) more accessible to people who might have difficulty using them. The Apple IIgs is very dependent on graphic objects, a keyboard and mouse; not all people can use these things very easily.

There are several components to Apple's Universal Access software:

How It Works (Access Nothing and Checks for Free)

Universal Access generally works by replacing Apple IIgs toolbox functions. For example, CloseView patches QuickDraw so you do not draw to the actual screen, but to another buffer that CloseView can then magnify. Video Keyboard patches the Window Manager so that its keyboard window is always frontmost and fully visible (and accessible). Easy Access uses the ADB tools and the Event Manager to alter the way the hardware responds.

Since Universal Access changes the way the tools behave, your applications do not have to work very hard to be accessible to a broad range of physically challenged people. Just by following the rules, you have an accessible application. There are, however, a few guidelines you should keep in mind when designing your programs to make them as accessible as they can be.

Universal Access Compatibility Guidelines

Further Reference

This and all of the other Apple II Technical Notes have been converted to HTML by Aaron Heiss as a public service to the Apple II community, with permission by Apple Computer, Inc. Any and all trademarks, registered and otherwise, are properties of their owners.