Lucent Technologies Inc.

Agere Systems Inc.

Agere Systems Guardian Corp.

James Frank Vomero

Frederick Harrison Fischer

Shaun Patrick Whalen

Kenneth Daniel Fitch

Avinash Velingker

Sucheta Sudhir Chodnekar

Bahram Ghaffarzadeh Kermani

William James Smurthwaite

A method and apparatus allowing two independent arbiters which do not directly talk to one another to function on a common system bus, allowing efficient operation of a master controller, and virtually endless capability to add peripherals to the common system bus without problems or major modifications commonly associated with additional arbitration overhead. A master controller sets time slot parameters for an external, subordinate arbiter as often as desired. Based on the time slot parameter information, the subordinate arbiter functions on an electrically separated portion of the common system bus during all times but for a time slot associated with communication of the super arbiter over the entire common system bus. During this time, a tri-state buffer element allows communication between portions of the common system bus. In an adaptive arbitration mode, the subordinate arbiter combines static time slot information assigned in configuration registers together with actual bus requests to generate grant signals to the requesting devices, and reassigns all or portions of time slots which, although assigned to a particular device, are left unused for the relevant system cycle. A historical buffer may be maintained for any or all time slots. Using this historical information, long term statistical information may be generated. Moreover, the master controller may re-tune time slot configurations based on the historical information regarding past recent use of the relevant time slots.

Hierarchical bus arbitration

A method and apparatus allowing efficient access control to a common data bus by including an isolation device to separate the common data bus, a priority-based arbiter to control access to the internal portion of the common data bus including a processor or other bus master, and a time slot arbiter to control access to the external portion of the common data bus including multiple bus masters, an external memory interface, etc. The common external memory may be allocated for exclusive or non-exclusive use by the various devices utilizing either portion of the isolated common data bus. External devices accessing the external memory may communicate directly with one or more bus masters, e.g., on the internal portion of the common data bus.

Shared devices and memory using split bus and time slot interface bus arbitration

A method and system for testing a circuit. A test program is downloaded into the circuit, which causes the circuit to provide a serial test output pattern comprising a series of identical signals to indicate whether the circuit passes the test. Signals of the test output pattern are compared against corresponding signals of an expected test output pattern only for non-masked signals of the expected test output pattern, wherein the expected test output pattern is masked for a maximum tolerable time period around an expected test output pattern start time.

Testing asynchronous circuits

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Catasauqua, PA, United States of America

James Frank Vomero