Apple PowerBook (Duo 270C) - Manual (Page 39)

Keyboard and trackball
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When you use the keyboard and trackball, your shoulders
should be relaxed. Your upper arm and forearm should form
an approximate right angle, with your wrist and hand in
roughly a straight line.
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You may have to raise your chair so your forearms and hands
are at the proper angle to the keyboard. If this makes it
impossible to rest your feet flat on the floor, you can use a
footrest with adjustable height and tilt to make up for any gap
between the floor and your feet. Or you may lower the
desktop to eliminate the need for a footrest. Another option is
to use a desk with a keyboard tray that’s lower than the
regular work surface.
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Use a light touch when typing or using the trackball and keep
your hands and fingers relaxed. When using the trackball,
avoid rolling your thumbs under your palms.
Some computer users may develop discomfort in their hands,
wrists, or arms after intensive work without breaks. If you
begin to develop chronic pain or discomfort in your hands,
wrists, or arms, consult a qualified health specialist.
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Change hand positions often to avoid fatigue.
This Not this
This Not this
Chapter 1: Setting Up Your PowerBook Duo 23