A memory device has a main memory circuit, an auxiliary memory circuit for storing test data, and an interface circuit for transferring test data between the auxiliary memory circuit and external test equipment. Test data are transferred from the external test equipment to the auxiliary memory circuit, then transferred repeatedly to different locations in the main memory circuit. Different test patterns are generated by selectively inverting one bit, or all bits, in the test data as the data are transferred into the main memory circuit. Test results are obtained by using a comparator in the memory device to compare the data stored in the auxiliary memory circuit with data read from the main memory circuit.
A method and arrangement is provided for testing memory external to a network switch and a memory interface bus connecting the external memory to the network switch. The method includes writing, via the memory interface bus and on a per-bit basis, a first prescribed logic pattern to a prescribed region of the memory to check for one of a bus short to ground and a short between adjacent pins of the memory. The first prescribed logic pattern is read to verify operation of the prescribed region of the memory. The method includes writing, via the memory interface bus and on a per-bit basis, a second prescribed logic pattern, complementary to the first prescribed logic pattern, to a prescribed region of the memory to check for one of a bus short to power and a short between adjacent pins of the memory. The second prescribed logic pattern is read to verify operation of the prescribed region of the memory.
A method and apparatus permits use of a tester memory (31) as storage for an inversion mask. The inversion mask indicates to the tester which cells in a DUT memory (14) are logically inverted during testing. Data information and the inverse of the data information is input into a first data multiplexer (802). The stored inversion mask (902-908) is used to independently select a data information bit or its inverse for presentation as a masked output (814) at the output of the first data multiplexer (802).
A system and method for determining data integrity as such data passes through a FIFO. A generator is provided for appending a bit in a predetermined bit location in each packet pushed into the FIFO in response clock signals. The appended bit is a function of the information pushed into the FIFO. A checker is provided for providing an indication of the information integrity in response to bits produced at an output of the FIFO in the predetermined bit location. In one embodiment, the generator is a parity generator and the checker is a parity checker. In one embodiment, during an initial test mode, one parity type is introduced into the FIFO by the parity generator and the opposite parity type is checked at the output of the FIFO by the parity checker to determine whether the parity checker is able to produce parity error signals. In another embodiment, the generator is a packet delimiter generator and the checker is a packet delimiter checker. In another embodiment, the generator is a frame delimiter generator and the checker is a frame delimiter checker.
The present invention allows for the reduction in power consumption of memory devices. A memory device in one embodiment prohibits address signal propagation on internal address buses based upon a function being performed by the memory. As such, some, all or none of the externally provided address signals are allowed to transition past address buffer circuitry.
