Abstract: A system for verifying the identification of a device. A codec is configured to measure at least one electrical characteristic of a device connected to a jack and to identify the device based on the measured electrical characteristic. An updateable database is populated with the electrical characteristic of at least one device whose electrical characteristic was measured by the codec but not correctly identified by the codec and a software routine is responsive to the measured electrical characteristic and configured to adjust the codec's identification of the device based on the electrical characteristic stored in the database to correctly identify the device.

Abstract: A system and method for determining the true electrical characteristics of a device. A codec is configured to measure at least one electrical characteristic of a device connected to a jack and to identify the device based on the measured electrical characteristics. An updateable database is populated with application circuit information and a software routine is responsive to the measured electrical characteristic and configured to adjust the electrical characteristics measured by the codec based on the application circuit information in the database.

Abstract: A keyboard bus is provided in a PC for connecting a peripheral such as a keyboard to a central unit, serially through external modules coupled to the bus enabling communication with the central unit by any of the external modules or the keyboard independently of other. The external modules are coupled serially to each other with a peripheral device, such as a keyboard, disposed most remotely from the central unit. The modules are serially connected in an open chain to the central processor for communication bidirectionally by an address signal to the intended respective module and an attention acknowledgment signal back to the central processor indicating a readiness for data reception.