Compaq Computer Corporation, Inc.

David E Murray

David R Wooten

Randall L Hess

Jeff W Wolford

Christopher C Wanner

A serial bus communications method and circuitry for low speed serial bus functions. Over a two-wire communications channel, a unidirectional clock line and a bidirectional data line are used to transfer data. A protocol defines permissions, acknowledgments, terminations and retries handshaking between points. Circuitry is provided for reducing the latency of the serial bus when cooperating with the low speed functions. A resistive connection scheme is disclosed for converting high voltage signals into lower voltage signals.

Low speed serial bus protocol and circuitry

A keyboard system according to the present invention includes a serial bus host controller coupled to a serial bus keyboard. The keyboard includes both keyboard scan logic and scan code conversion logic for passing to the host controller over the serial bus. The host controller includes circuitry for processing the data between the serial bus and a host bus. The host controller further includes 8042 emulation logic for providing a hardware compatible interface to the keyboard controller. The 8042 emulation logic also includes circuitry for communicating over the serial bus during times when the serial bus has not yet been initialized.

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Houston, TX, United States of America

David E Murray