Advanced Micro Devices Corporation

James Bunnell

Larry David Hewitt

Paul C Miranda

David E Norris

A USB host controller provides transaction type status signals indicating USB activity type. The status signals include a bulk status bit signal indicative of bulk activity on a USB, a control status bit signal indicative of control activity on the USB, an isochronous status bit signal indicative of isochronous activity on the USB and an interrupt status bit signal indicative of an acknowledged interrupt on the USB. In addition a programmable mask register is provided for masking any or all of the status bits. The status bits may be combined and provided as a single signal indicative of USB activity.

Method and apparatus for monitoring universal serial bus activity

Power consumption is conserved in a computer system by, instead of forcing a processor to change from the stop clock state to a fully operational state, allowing the processor to transition from the stop clock state to the stop grant state. The stop grant state allows snoops so that the processor handles subsequent bus cycles and snoops that take place during the bus cycles. Following the snoops, the processor transitions back from the stop grant state to the stop clock state. In one embodiment, an automatic control circuit is connected to a processor in a computer system. When the processor is in the stop clock state, the automatic control circuit responds to a bus request, not by transitioning to the fully operational state, but instead by transitioning from the stop clock state to the snoopable stop grant state in which the processor clock is operating. The automatic control circuit allows the snoop to take place then, when the snoop is complete, automatically transitions the processor back to the stop clock state.

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LaFayette, CO, United States of America

James Bunnell