METHOD FOR KEY SCANNING OF KEYBOARD

PURPOSE:To prevent a key input from being missed by detecting the state of another key at the time of depressing another key during the depression of a depression-effective key, removing chattering, setting a depression processing waiting state, and after the open processing of the depression-effective key, continuing the depression of another key. CONSTITUTION:Even in the depressing of a key A, other key scanning can be continuously executed and the depression of a key B can be detected at the time of initial key scanning. After removing key chattering, a depression processing waiting state is set. When the key A is opened and the open processing of the key A is executed, the key B in the depression processing waiting state can be successively depressed. Even in the depression of the depression-effective key, another key can be scanned and shattering removal can be also executed by utilizing the interval of the key scanning to be continuously executed. Even if another key is depressed during the depression of the depression-effective key, the key in the processing waiting state can be depressed continuously after the open processing of the depression-effective key, so that the key input is not missed.