From the Control Panel on the Apple IIGS, one can set many of the system
configuration settings stored in the battery RAM. These include such settings
as screen color, microprocessor speed, slot assignment, and others. However,
one of the configurable settings that is not included as an option in the
Control Panel is the screen refresh rate.
Because the Apple IIGS is an international machine, it must be able to
conform to European standards. In Europe, the screen refresh rate is 50 Hz,
rather than 60 Hz as defined by the U.S. standard.
In order to change the screen refresh rate, one must enter the "Super"
Control Panel. This control panel is kept separate from the regular Control
Panel for safety reasons. No harm will come to the Apple IIGS or the monitor
if the refresh rate is incorrectly set. However, the screen display may
become unreadable as long as the incorrect mode is set. The Super Control
panel was made less accessible so that it would be more difficult to
accidentally change the setting.
Entering the Super Control Panel is done by re-booting the computer in a
special way. Rather than pressing Open-Apple/CTRL/Reset, the normal key
sequence for rebooting, simultaneously press OPTION, CTRL, and Reset.
The computer will cold start and then display the Super Control Panel screen.
From there one can change the screen refresh rate, enter the regular Control
Panel, or continue with the boot process.