| 摘要 |
A keyboard access system is provided for interfacing a keyboard and the programs of a text processing machine. The keyboard has typamatic function keys, i.e., nontypamatic keystroke information is generated by the keyboard upon depression of a key and, after a short delay, additional typamatic keystroke information is generated as long as the key is held down at a constant rate. The keystroke information represents a key on the keyboard and may also represent the meaning of the key as determined by the state of one or more prefix keys. A keystroke queue is provided for storing keystroke information passing through the keyboard access system. If the keystroke information entered into the keyboard access system is not typamatic, the system will enqueue the information in the keystroke queue and generate an audio feedback signal when the keystroke queue is not full. If the keystroke information is typamatic, the keystroke information will be compared to a table of valid typamatic function keys. If a comparison does not exist, the keystroke information is discarded. If a comparison does exist and the meaning of the key is acceptable, the keystroke information is enqueued if the preceding keystroke enqueued is no longer stored in the keystroke queue and discarded if the preceding keystroke is enqueued and currently stored in the keystroke queue and also represents the key to prevent excess information from being stored in the keystroke queue. This prevents operator overrun while using keys such as the vertical and horizontal cursor. In addition, the provision of a slow typamatic function rate permits the operator to read the text on a display while using a vertical cursor key.
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