Pressing Start on Controller 2 toggles frame advance.
Controls when frame advance is enabled:
If neither L nor R is pressed/held on Controller 2, gameplay stops.
When holding L or R on Controller 2 (with the exception below), gameplay runs at one fifth speed (one frame of gameplay every five actual frames, starting when the game registers the L button press or when the phase below ends, whichever happens last).
On pressing R on Controller 2, gameplay advances one frame and then is forced to stop for 32 frames (slightly more than half a second) or until L and R are released, whichever happens first, then controls apply as above.
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