The reset_pb signal is used to restore the Aurora 64B/66B core to a known starting state. Upon reset, the core stops the current operation and re-initializes the channel. It is expected that user_clock is stable when the reset_pb signal is applied. When the reset_pb signal to the Aurora 64B/66B channel partner1 is asserted, channel partner2 also loses lock. Channel partner2 regains lock when channel partner1 is out of reset and begins transmitting valid patterns. On full-duplex cores the reset_pb signal resets both the TX and RX sides of the channel. simplex Aurora 64B/66B cores have similar reset_pb ports for both partners and require a different reset sequence. Asserting pma_init resets the entire serial transceiver which eventually resets the Aurora 64B/66B core as well. Also, it is assumed init_clk is always stable and the ref_clk is stable at the time of deassertion of the pma_init signal.