PURPOSE: To attain the multi-stage speed control of a key repeat speed in a computer system having a keyboard input by a rule optionally defined from data.

CONSTITUTION: The generation of key repeat is detected by a key repeat detecting part 13, and in order to determine its key repeat speed, environment information such as a cursor position and character information around the cursor are collected and evaluated by a key repeat speed inference engine 14 based upon a key repeat control rule 15. The inferred result is written in a fixed address of a storage device 16 and a control part 17 always refers to the inferred result to determine a key repeat cycle. Since the rule 15 is stored in a nonvolatile RAM, it can be rewritten. Since the engine 14 is independent of the control part 17, no load is applied to a control device by interruption due to the generation of key repeat.