Agere Systems Inc.

Han Nguyen

Avinash Velingker

Hyun K Lee

Shaun Patrick Whalen

Michael Richard Betker

Jay Patrick Wilshire

Richard Niescier

Bryan Schlieder

Lai Q Pham

Manosha S Karunatilaka

A method and apparatus are disclosed for dynamically reducing clock skew among various nodes on an integrated circuit. The disclosed clock skew reduction technique dynamically estimates the clock delay to each node and inserts a corresponding delay for each node such that the clock signals arriving at each node are all in phase with a global clock (or 180&#xb0; out of phase). Delays attributable to both the wire RC delays and the clock buffer delays are addressed. A feedback path for the clock signal associated with each node allows the round trip travel time of the clock signal to be estimated. When the length of the feedback path matches the length of the primary clock path, the clock skew present at the corresponding node can be estimated as fifty percent (50%) of the round trip delay time. Dynamic adjustments to the delay control circuit are permitted as operating conditions shift. Clock signals arriving at individual nodes on the integrated circuit remain in phase with the global PLL clock (PCK), regardless of variations in the operating voltage or temperature (or both).

Method and apparatus for distributing a self-synchronized clock to nodes on a chip

Techniques are disclosed for implementing software breakpoints in a multiprocessor system having a number of processors each coupled to a main memory. In an illustrative embodiment, each of the processors has an instruction cache associated therewith. An instruction for which a breakpoint is to be inserted is retrieved from a corresponding instruction address in the main memory, and a breakpoint code is inserted at the instruction address in main memory. After the breakpoint code is executed by a given one of the processors, the retrieved instruction is stored in the corresponding instruction cache for that processor, and a use-once indicator is set. The use-once indicator is operative via cache control logic to clear a validity indicator associated with the instruction after a single fetch of the instruction from the instruction cache, such that subsequent attempts by the given processor to access the instruction as stored in the instruction cache will cause the processor to retrieve the breakpoint code at the instruction address in main memory.

Multiprocessor system with cache-based software breakpoints

A time division multiplexing (TDM) method and apparatus for interfacing data from communication channels to a TDM bus. The TDM arrangement uses a shift register to control a tri-state buffer. The shift register regulates the tri-state buffer based on a data bit pattern loaded into the shift register. The data bit pattern corresponds to the status of the individual channels. Each channel is assigned a bit which indicates whether the channel is active or inactive. As the shift register shifts out data, the tri-state buffer allows data to flow onto the TDM bus when a bit indicating an active channel is present and insulates the TDM bus from the communication channels when a bit representing an inactive channel is present. A processor is used to control the interrelationship of the multiple communication channels and to generate the status bits to be loaded into the shift register. The processor fills the shift register through the use of a storage register. In a preferred embodiment, the shift register is capable of shifting out a sufficient number of bits to fill an entire transmission frame operating in T1 (24 channels), E1 (32 channels), 64-slot (64 channels), and 128-slot (128 channels) transmission modes. In addition, the tri-state buffer may perform the additional function of level shifting the voltage level of the data from the multiple communication channels to a level compatible with the TDM bus.

Method and apparatus for interfacing multiple communication devices to a time division multiplexing bus

A time division multiplexing (TDM) method and apparatus for interfacing data channels with a TDM bus. The TDM interface uses a processor and a channel coordinator circuit to indicate which data channels are active, and to assign which TDM transmit channels and which TDM receive channels will correspond to the active data channels. The processor controls the flow of data by using a channel coordinator circuit which controls multiple shift registers. The multiple shift registers control the flow of data between the active channels and the TDM bus. Multiple storage registers are used to buffer the data flowing between the active channels and the shift registers.

Method and apparatus for interfacing multiple data channels to a bus

Disclosed is a method and apparatus for accomplishing high speed multiplication of binary numbers using a single clock cycle to achieve the same computational power provided by the multiple clock cycle shift register configurations or the asynchronous multistate logic configurations of the prior art. &ldquo;Virtual shifts&rdquo; are achieved by allocating one or more positions, within a register storing the partial products, as place holders, typically zeroes. These place holders can be inserted in a single clock cycle and do not require the multi-staged shift register configurations of the prior art.

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Allentown, PA, United States of America

Han Nguyen