Apple Power Macintosh 5200/75 LC - Manual (Page 41)

Using the screen control buttons on your computer
You can adjust the level of light and dark on the screen of your built-in
monitor by using the screen control buttons on your computer (marked with
the ¸ icon).
m Press the button on the right to lighten your screen.
m Press the button on the left to darken your screen.
Screen control buttons
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33 Expanding Your Computer and Using Special Features