Abstract: A line card provides terminating resistors for a bus or traces on a backplane. The line card terminations are activated (connected to ground) by a crossbar switch that is set according to programming (software/firmware/flash memory stored instructions) maintained on the line card to set the state of the resistive terminations. The programming maintained on the line card may be downloaded to the card into nonvolatile storage. The decision to utilize a specific line card to terminate or leave the bus unterminated is made by a control unit that sends command messages to the line card. A polling device interrogates each line card and sets the physically last card on the bus as a terminating card. The command messages are in ADSL Provisioning Message format and transmitted to each line card via a CPU Cell Data Link (CCDL).

Abstract: A retiming circuit is provided which accurately converts half-width dual rail data with up to one unit interval of jitter with respect to the data clock, into full-width data. The circuit is comprised of D-flip-flops and associated logic elements which capture and hold a data pulse until the captured data pulse can be accurately transferred to the next circuit stage by a positive clock transition.