Here are some thoughts from The Computer Museum's Director of Design; one
note in connection with his comment regarding the large-ball trackball:
the introductory interactive for the Boston MFA's Minor White exhibit
(interactive and exhibit both, outstanding, by the way) incorporates such
a trackball, with a gracefully designed plate covering j-u-s-t enough
of the trackball to prevent removal.
 
Brian Wallace
Manager Historical Collection/Media Arts Exhibit Developer
The Computer Museum
 
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--------------------------------- ATTACHMENT ---------------------------------
 
Date: 9 Aug 94 18:50:00 EDT
From: "Ted Groves" <[log in to unmask]>
Subject: RE: ideas
To: "Brian Wallace" <[log in to unmask]>
 
The requirements for ADA compliance are the same for all workstations, whether
you use a trackball or a keyboard. I'll pass along the Massachusetts
Architectural Access Board regulations, which I use, and which are in nearly
every case more stringent than the federal requirements. The counter top must
allow at least 27" clearance from the floor to its lowest edge, with a tabletop
height of 32". There must be at least 22" of depth between the front of the
counter and the wall. There must be at least 30" wide knee space from side to
side. The top of any shelf must be at a height no greater than 38" above the
floor. Operable controls must be located at a height no greater than 54" above
the floor. A good rule of thumb for any operable control is that it should be
able to be used with a closed fist. Both the trackball and mouse are fair for
this; touchscreen controls are slightly better if the buttons used are more than
1.5" square. Its also a good idea to utilize sound as much as possible in
multimedia presentations for the benefit of visually impaired users, who ideally
are accompanied by someone who explains the visuals. One last note: the
Kensington Turbomouse is a good trackball to use for public displays due to its
large ball and buttons. People will once in a while figure out that the balls
are removable, but they're cheap and easy to replace.
 
I hope this is helpful,
 
Ted Groves
Director of Design
The Computer Museum