Abstract: A hybrid shift register latch which uses static memory cells for system operations and a dynamic memory cell for testing operations only. An L1 storage element and an L2 storage element are provided in an array cell. The L1 storage element comprises a static random access memory cell. The L1 storage element is used during system and testing operation of the array cell. The L2 storage element comprises a dynamic random access memory cell. The L2 storage element is used only during testing operation of the array cell.

Abstract: A hybrid shift register latch which uses static memory cells for system operations and a dynamic memory cell for testing operations only. An L1 storage element and an L2 storage element are provided in an array cell. The L1 storage element comprises a static random access memory cell. The L1 storage element is used during system and testing operation of the array cell. The L2 storage element comprises a dynamic random access memory cell. The L2 storage element is used only during testing operation of the array cell.

Abstract: An apparatus and method is provided that combines both self test and functional features in a single latch circuit, which may be used with an SRAM array and is usefully embodied as an L1-L2 latch. During partial writes from an SRAM array, data bits of unknown state are inhibited from entering the latch circuit, while data for testing is allowed to enter. In one useful embodiment of the invention the latch circuit is used with a mode control that provides mode select signals to operate the latch circuit in one of a plurality of modes, including at least full write and partial write modes. The latch circuit further includes a data hold circuit for selectively receiving and storing data coupled to the latch circuit. A first enabling circuit responsive to the mode select signals enables the hold circuit to receive all the data contained in the array during a full write mode, and further enables the hold circuit to receive only some of the data bits contained in the array during a partial write mode.

Abstract: Repairing arrays on a processor with an on chip built in self test engine on the processor is provided. A subset of the arrays is selected for testing. Data patterns are sent from the test engine to the subset of arrays at a plurality of operating parameters. A response is received at the test engine from the subset of arrays at the operating parameters. The received response is compared to an expected response using the test engine, wherein the processor controller determines if additional test failures were detected by the test engine for the subset of arrays with a plurality of JTAG based instructions. Code in the processor controller then determines the states that need to be scanned into the scannable latches to force the array control logic to choose additional spare wordlines and/or bitlines to repair the newly identified failures in addition to all previously defined repair actions.

Abstract: Each match word line driver circuit associated with a content addressable memory (CAM) utilizes a scannable latch for testing. The scannable latches associated with a particular CAM are connected together, scan output of one to scan input of the next, forming a scanning latch chain. In test mode the scannable dynamic latch is used either for testing CAM match circuits or for driving word lines to test the RAM array. Testing CAM match circuits is accomplished by patterning the CAM array with known storage values. The match circuitry then compares an effective address to each storage value and the results are scanned out. Testing the RAM array is performed by driving each word line with a known scan value. Each word line responds the scan value and a sense amplifier outputs a RAM array value based on the word line.

Abstract: A method and apparatus for testing a plurality arrays on a processor with an on chip built in self test engine on the processor. A subset of the plurality arrays on the processor is selected for testing using a control mechanism to selectively enable testing of the subset. Data patterns from the on chip built in self test engine are sent to the plurality arrays on the processor. A response is received at the on chip built in self test engine from the plurality arrays. The response from the plurality arrays is compared to an expected response using the on chip built in self test engine.

Abstract: The present invention adds a programmable expect generator (PEG) that generates expected patterns of output for comparison to the actual outputs of an array while undergoing a complex test input sequence. The output of a programmable array built-in self test (PABIST) controller has its output increased to include separate control bits and a mask bit for a PEG. The PEG in one embodiment of the invention is substantially similar to a data control register that is programmed by a sequence of commands to generate the array input data patterns for testing an array. The program sequence that controls the PABIST and generates the input address, data and read/write patterns also outputs separate control bits to direct the PEG to generate expected outputs from the array when data from corresponding read addresses are read. The incorporation of a mask bit that accompanies each group of PEG control bits is used to inhibit the compare function that compares the output of the array to the output of the PEG.

Abstract: The present invention discloses a method and system for testing imbedded logic arrays. An imbedded logic array is first tested for read/write functionality and then a test sequence is run to test the imbedded logic function. The method of the present invention writes a first data pattern to all addresses in an imbedded logic array. Next a second data pattern is written to a specific address followed by a read selecting all addresses concurrently. The output of the imbedded logic array, during this test, is the logic combination of the first data pattern and the second data pattern at the address where the second data pattern was written. By comparing the imbedded logic array output to an expected output the imbedded logic of the array is tested. The present invention anticipates imbedded logic arrays where the expected data output is not a previously written pattern.

Abstract: A method and apparatus for testing a contents-addressable-memory type structure using a simultaneous write-thru mode in an array is provided. The circuit to be tested has combinational logic and an array, and the array has bit cells and a logic cells. Each logic cell is uniquely associated with a bit cell such that an output of a bit cell provides an input to a logic cell, and each set of logic cells for an address of the array provides an output data vector from the array. Each cone of logic in the combinational logic receives an output data vector from an associated address in the array as an input data vector, and each cone of logic in the combinational logic is independent from other cones of logic in the combinational logic. A test vector is input to a write port of the array, and a set of logic cell input values are also input into the array.