Nintendo GAME BOY Programming Manual page 262

Game Boy Programming Manual
3.3.5 Limiting the Period of Continuous Vibration (Recommended)
To prevent physical effects in the user such as numbness as a result of continuous vibration, limit
the duration of continuous vibration as indicated below, regardless of the vibration strength.
! Limit the duration of continuous vibration to 1 minute.
! If the nature of the game makes longer periods of continuous vibration unavoidable, limit
these periods to 3 minutes.
3.3.6 Rumble Feature Selection (Recommended)
The user should be allowed to set the rumble feature to ON or OFF or to select strong, mild, or
OFF by means such as an initial-settings screen at the start of the game. In addition, the program
should allow the user to easily change these settings even during a game if, for example, they are
uncomfortable with the vibration. Such changes also should be allowed a pause.
3.3.7 Changes in Vibration Level with Battery Use (Recommended)
If the battery that powers the motor (size AAA alkaline battery) wears out, the perceived vibration
level will be reduced even if the requested vibration level remains the same. Therefore, rumble
operation should be checked both when the battery is new (1.6 V) and when it is at the end of its
life (1.1 V).
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