Keyboard cascading method for computer system

摘要

The method involves operating more than one keyboard as input medium in a computer system, especially in a personal computer. A first keyboard (T1), the root keyboard, is connected with its standard ATO3 interface (SS1) in the usual way with the computer system (PC), and comprises a second, additional interface (SS2) which corresponds to the standard ATO3 interface, at which a second, external keyboard (T2) is connected. The second keyboard is likewise be connected over an additional interface with a third keyboard (T3), whereby this cascading can be performed for an arbitrary number of keyboards. The control is performed through microprocessors (MP) installed in the keyboards, which operate a synchronous data transmission to the computer system. When recognizing a connected external keyboard (T2, T3, T4) in an initialization phase, it is switched through instructions into a SCAN-CODESET 3 for MAKE/BREAK key treatment. The dependencies available in the standard use, i.e. the scan code set chosen by the computer system, the repeat durations and special treatments, are stored only in the microprocessor of the root keyboard. The key codes transferred by the external keyboards in the scan code set 3 mode are converted by the microprocessor of the root keyboard and transmitted to the computer system.