Abstract: Instead of alternatively utilizing only one fabric or the other fabric of a redundant pair, both fabrics simultaneously transmit duplicate information, such that each packet forwarding module (PFM) receives the output of both fabrics simultaneously. In real time, an internal optics module (IOM) analyzes each information chunk coming out of a working zero switch fabric; simultaneously examines a parallel output of a working one duplicate switch fabric; and compares on a chunk-by-chunk basis the validity of each and every chunk from both switch fabrics. The IOM does this by examining forward error correction (FEC) check symbols encapsulated into each chunk. FEC check symbols allow correcting a predetermined number of bit errors within a chunk. If the chunk cannot be corrected, then the IOM provides indication to all PFMs downstream that the chunk is defective. Under such conditions, the PFMs select a chunk from the non-defective switch fabric.

Abstract: A system for testing an integrated circuit. The system includes a plurality of simultaneous switching output (SSO) cells with each of the plurality of simultaneous SSO cells including an output driver providing an output signal to a respective signal pin coupled to the integrated circuit, a toggle circuit toggling its output; a multiplexer selecting a signal for communication to the output driver to control output provided to the respective signal pin, an input signal line communicating an SSO enable signal to the multiplexer, wherein the multiplexer selects the toggled output for communication to the output driver when the SSO enable signal is asserted; and a signal pin that is coupled to each respective input signal line of the plurality of SSO cells.

Abstract: The inventive circuit allows the circuit to be used either to create a simultaneously switching outputs (SSO) event or to create a simultaneously switching inputs (SSI) event. The circuit uses a toggle register to generate a toggling signal and a signal line to operate logic to select the toggling signal as output from the circuit for the SSO event. The signal line is connected to an external pin. The circuit uses another signal line, also connected to an external pin, to disable or tristate the output driver that drives the I/O pin. This permits the circuit to receive input for the SSI event. Two chips, each having a plurality of such circuits, can be arranged so that one chip generates the SSO event and sends it to the second chip, which is configured to receive the SSI event. The circuit also has a pair of registers in a cascade arrangement to provide precise control of the output signal.

Abstract: The inventive system and method determines path delay of at least one test path of logic gates. The invention uses a toggle register to generate a toggling signal, that is sent out onto the path by a launch register. A capture register receives the signal from the other end of the path. A logic gate compares the received signal from a prior launched signal with an inverted launched signal. Since the signal is a toggling signal the prior received signal should be the same as an inverted launched signal. A latch register determines whether the logic gate has detected a match between inverted launched signal and the received signal from a prior launch signal within a predetermined time clock period. As the clock period is shortened, the launched signal will fail to traverse the path and be captured by the capture register within the clock period. This will cause a mis-match in the logic gate. The clock period at the point of mis-match is the delay time of the path.