Abstract: An apparatus and method for providing a back out routine for a failed programmable hardware update is provided. In one embodiment, the method includes: a) storing a new software image for the programmable device associated with the hardware update, b) storing a previous software image for the programmable device, c) programming the programmable device to operate according to the new software image, d) determining if there is a failure associated with the programming step, and e) if a failure is identified, programming the programmable device to operate according to the previous software image, otherwise the hardware update to the programmable device was successful. In one aspect, the back out routine is provided for a program load failure. In another aspect, the back out routine is provided for a programmable device failure.

Abstract: A data shift register receives and stores each time sample (digital word) carried by an inbound channel. A selector chooses for each time slot either the input digital word received during the same time slot or the digital word stored in the shift register during the previous time slot. This selected digital word is transmitted on an input channel to a concentrator. The selector is controlled by data stored in a control shift register which causes the selector to make its selection.

Abstract: A tone burst generator where a continuous tone voltage is applied across two series-connected semiconductor switches each having an ON state and an OFF state. A first control circuit controls the state of the first switch and the variable impedance in an intermediate region between its ON and OFF states to cause gradual, well-defined OFF/ON and ON/OFF transitions of the first switch. As a result of these first switch transitions, a voltage tone burst is generated that has precisely defined edges to eliminate clicking noise. The continuous tone voltage is of only one polarity--it has a non-zero DC component and an AC component having a peak-to-peak variation less the twice the magnitude of the non-zero DC component. A second control circuit controls the state of the second switch and the variable impedance in an intermediate region between its ON and OFF states to cause well defined ON/OFF and OFF/ON transitions of the second switch.