International Business Machines Corporation

Jonathan Yang Chen

Patrick James Meaney

Michael F Fee

Christopher J Berry

Alan P Wagstaff

Kevin Charles Gower

Frank David Ferraiolo

David Allan Webber

William J Scarpero, Jr

Timothy John Slegel

Gary A Van Huben

Mark Anthony Check

Jose Luis Neves

David L Rude

Vern Anthony Victoria

Glenn E Holmes

Thomas E Gilbert

Jeffrey A Magee

Derrin M Berger

Thomas G Foote

Nathan A Dotson

A method for reducing logic and delay within a logic structure that includes searching logic structures to be analyzed, finding a plurality of latches within a logic structure to be analyzed, determining if any respective latches of the plurality of latches have sufficiently positive slack within an input and output path thereof and optionally excluding the respective latches from being analyzed, determining if there is at least one remaining latch to be analyzed, and determining whether inverters are disposed within an input path and an output path of the at least one remaining latch. The method further includes obtaining logic functions of the input path and output path of the at least one remaining latch when inverters are found, modifying the logic functions using DeMorgan's Theorems, determining whether timing violations exist with the modified logic functions, and annotating hardware description language based on the modified logic functions when no timing violations exist.

Reduction of logic and delay through latch polarity inversion

A method for modifying an integrated circuit and integrated circuits are provided. The method includes: providing an integrated circuit design comprising a plurality of circuit books having a first threshold voltage; and replacing at least one of the plurality of circuit books with at least one gate array book having a second threshold voltage that is lower than the first threshold voltage.

Method and system for changing circuits in an integrated circuit

A system and method to organize and use data sent over a double data rate interface so that the system operation does not experience a time penalty. The first cycle of data is used independently of the second cycle so that latency is not jeopardized. There are many applications. In a preferred embodiment for an L2 cache, the system transmits congruence class data in the first half and can start to access the L2 cache directory with the congruence class data.

Early directory access of a double data rate elastic interface

A double data rate elastic interface in which programmable latch stages provide an elastic delay, preferably on the driving side of the elastic interface. However, the invention is not limited to the driver side/chip, it can be implemented in the receiver side/chip as well. However, since the receiver side of an elastic interface already has complicated logic, the invention will be usually implemented on the driving side. The programmable latch stages on the driving chip side of the interface, can often operate at the local clock frequency (the same frequency as the elastic interface bus clock frequency), which in turn is half of the double data rate at which the receiving latch stages operate, thereby decreasing the logic and storage resources in the interface receivers. The programmable latch stages can also be used in the case that the local clock frequency is twice the elastic interface bus clock frequency.

Programmable bus driver launch delay/cycle delay to reduce elastic interface elasticity requirements

A double data rate interface in which the set-up interval is extended for a data path in which data is delayed relative to the other data path. Data is latched into a register comprised of mid cycle type latches, such as for example L2* latches. For example, if the delayed half of the data is not available until the second half of the double data rate cycle, the second half of the data is allowed to have a set-up interval around the mid cycle point while the on-chip timing logic launches the least delayed half of the data on the clock edge after it is set up, without waiting for the expiration of the set up interval of the delayed data.

Late data launch for a double data rate elastic interface

A system and method in which the receiving chip separately latches each half of the data received from the double data rate bus. Each half is launched as soon as it is available; one on the normal chip cycle time and the other is launched from a Master (L1) latch a half cycle into the normal chip cycle time. The first launched half of the data proceeds through the chip along its standard design chip path to be captured by the chips driving interface latch and launched again after one cycle of latency on the chip. The second half of the data proceeds through the chip one half cycle behind the first half, and is latched a half clock cycle later part way through the path into a Slave (L2) latch. On the next edge of the local clock, the data then continues from the L2 latch to the driving double data rate interface. This allows a half cycle set up time for the second half of the data so that it can be launched again, maintaining a one-cycle time on the chip.

Double data rate chaining for synchronous DDR interfaces

In a computer system with multiple chips connected via a connection module with high speed elastic interface buses that support bus repair is enhanced by use of a spare net. Support is provided to ensure that the spare net can be tested in the same way that every normal bus net can be tested at all supported environments. It ensure that the system controller can find out what connections are bad and how to apply the controls to repair them for all tests and in the field for the customer.

System and method to support use of bus spare wires in connection modules

A double data rate launch system and method in which the two-to-one multiplexer select signal delay is programmable and can be adjusted individually for each system. This allows the amount of delay to be minimized based on the actual set up time required, not the worst-case set-up time. The select signal to the multiplexer is delayed sufficiently to compensate for non-uniformity of duty cycle of data at the inputs to the multiplexer. Compensation of the non-uniformity allows the data on the wire to have a uniform duty cycle for all data transferred regardless of which latch is sourcing the data. The multiplexer that selects data from the two latches which are launching data on the edge of different clocks has a select line that is delayed by a variable amount to tune the select such that the data is clean at the input to the multiplexer on all ports.

Mechanism for windaging of a double rate driver

A method and hardware design is disclosed for allowing the bring-up of a large scale system of interfaces that need to undergo a sequence of calibration steps. The method involves the use of a flexible broadcast scheme whereby groups of interfaces within a chip are assigned to groups to which commands can be broadcast. The scheme allows for the maximum amount of flexibility, allowing interfaces to be assigned to multiple groups which can overlap and be subsets of one another, and still allows for groups to be excluded from broadcast commands and be access individually. A method is also disclosed for using a chip-global status summary that can be accessed as any other register on the chip and can report calibration results for an entire chip with only one command. According to the invention a service utilizing the method embodied with code for implementing the method can now be provided.

Method and service and computer program code for broadcast of interface group bring-up in a multiprocessor computer system having multiple nodes

A method of calibrating an elastic interface is provided to automatically achieve a minimal cycle delay through the interface. An existing self-alignment interface (i.e. elastic interface) is used to de-skew within a cycle and stage the data to have it arrive on a given, programmed target cycle. However, this target cycle must be calculated in advance and may be larger than it needs to be, causing more latency on the interface. This method is used to determine the earliest target cycle (with or without additional guard-band). This target cycle is used to adjust the interface automatically to achieve this earliest target cycle. The determination of earliest target cycle can be done once, continuously, or using a sample window. The method also can be used for interfaces that have frequency multipliers or phase shifts at its boundaries.

Method for receiver delay detection and latency minimization for a source synchronous wave pipelined interface

A method of calibrating an interface is provided to automatically achieve a minimal cycle latency while maintaining synchronous data arrival between a multiplicity of self-aligning interfaces. Independent self-alignment interfaces may de-skew data bits and have them arrive on a minimum cycle boundary. However, if all the interfaces do not arrive on the same cycle, SMP designs may not function properly. For instance, with a single control chip and multiple data chips on an AMP node, the control chip often sends out controls to the dataflow chips. If the data arriving on the elastic interfaces is not synchronized with the controls, the data is not routed properly. The method employs a calibration pattern to determine the latest cycle that data is received across the elastic interfaces and calculates the target cycle for all the interfaces to match this latest cycle. The target cycle is fed back into the design and the data is received synchronously, also provided is a test to ensure that the data arrives synchronously.

Digital system having a multiplicity of self-calibrating interfaces

An SMP computer system has an apparatus and method for recalibrating a self-timed, source-synchronous, pipelined interface while the computer system is running. The apparatus allows for quiescing the interface (ie. idling the processors to allow for no data transfers), raising fences (blocking interfaces), allowing for a quick clock centering recalibration step, and then unfencing and unquiescing to allow for the use of the interface again. The recalibration allows for compensating for drift over time on the interface to compensate for temperature, voltage, cycle time, and end-of-life degradation without bringing down and restarting the system.

Apparatus and method for recalibrating a source-synchronous pipelined self-timed bus interface

An automatic delay detection and receiver adjustment method for a synchronous communications bus system sends a test pattern to the receivers of the system during a detection phase, uses the test pattern to determine a longest delay time for each bus lone, and adjusts a receiver for each bit line to receive incoming signals at a time based on the determined longest delay time.

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Marlboro, NY, United States of America

Jonathan Yang Chen