Abstract: Transferring data from a first clock domain to a second clock domain, wherein the second clock domain has a fixed clock frequency, and the first clock domain has a variable clock frequency. The first clock domain and the second clock domain operate in a synchronous mode when the variable clock frequency is equal to the fixed clock frequency, and in an asynchronous mode when the variable frequency is lower than the fixed frequency. A first buffer and a second buffer are used for a data transfer from the first clock domain to the second clock domain. The second clock domain comprises a multiplexor connected to the first buffer and the second buffer. The multiplexor forwards data from the first buffer further into the second clock domain in the synchronous mode and from the second buffer into the second clock domain in the asynchronous mode.

Abstract: Transferring data from a first clock domain to a second clock domain, wherein the second clock domain has a fixed clock frequency, and the first clock domain has a variable clock frequency. The first clock domain and the second clock domain operate in a synchronous mode when the variable clock frequency is equal to the fixed clock frequency, and in an asynchronous mode when the variable frequency is lower than the fixed frequency. A first buffer and a second buffer are used for a data transfer from the first clock domain to the second clock domain. The second clock domain comprises a multiplexor connected to the first buffer and the second buffer. The multiplexor forwards data from the first buffer further into the second clock domain in the synchronous mode and from the second buffer into the second clock domain in the asynchronous mode.

Abstract: A computer implemented method and data processing system are provided for preventing firmware defects from disrupting logic clocks. In response to a firmware interface requesting a scan operation for a functional unit, protection logic allows a scan enable to activate to the functional unit only if the logic clocks are stopped to that functional unit, otherwise the scan enable is not activated, an error is indicated, and an interrupt is presented to firmware. Also, in response to a command from a firmware interface to stop the logic clocks to a functional unit, protection logic allows the clocks to be stopped to the functional unit only if the functional unit is already indicating a catastrophic error, otherwise the clocks are not stopped, an error is indicated, and an interrupt is presented to firmware.

Abstract: A computer implemented method and data processing system are provided for preventing firmware defects from disrupting logic clocks. In response to a firmware interface requesting a scan operation for a functional unit, protection logic allows a scan enable to activate to the functional unit only if the logic clocks are stopped to that functional unit, otherwise the scan enable is not activated, an error is indicated, and an interrupt is presented to firmware. Also, in response to a command from a firmware interface to stop the logic clocks to a functional unit, protection logic allows the clocks to be stopped to the functional unit only if the functional unit is already indicating a catastrophic error, otherwise the clocks are not stopped, an error is indicated, and an interrupt is presented to firmware.

Abstract: A method and apparatus for operating a clock in a processor having asymmetrically mirrored base-mirror units is disclosed. The method includes initializing a base-unit and a mirror-unit of the processor to the same state, and starting the mirror-unit-clock one clock cycle later than the base-unit-clock.

Abstract: A method and apparatus for operating a clock in a processor having asymmetrically mirrored base-mirror units is disclosed. The method includes initializing a base-unit and a mirror-unit of the processor to the same state, and starting the mirror-unit-clock one clock cycle later than the base-unit-clock.

Abstract: An exemplary embodiment of the invention is a method of characterizing capacitances of a plurality of integrated circuit interconnects. The method includes coupling a first oscillator to a first integrated circuit interconnect and coupling a second oscillator to a second integrated circuit interconnect. The first oscillator is activated to characterize the sum of (i) coupling capacitance between the first integrated-circuit interconnect and the second integrated-circuit interconnect and (ii) ground capacitance between the first integrated-circuit interconnect and a ground. In addition, both of the first oscillator and the second oscillator are activated to characterize the ground capacitance between the first integrated-circuit interconnect and the ground.