Programmable bit rates in a constant bandwidth TDM switch

A time division multiplexing (TDM) digital switch adapted to receive a plurality of serial input TDM streams and to transmit a plurality of serial output TDM streams, each serial input TDM stream having a respective input data rate not greater than a maximum data rate, the TDM digital switch comprising:

• a. a plurality of input shift registers, each for receiving a corresponding one of the serial input TDM streams and generating a corresponding parallel input stream, each parallel input stream belonging to one of a plurality of parallel input stream subsets (PIS subsets);
• b. a plurality of output shift registers, each for receiving a corresponding parallel output stream and transmitting a corresponding one of the serial output TDM streams at a respective output data rate
• c. a data selector for multiplexing the parallel input streams in each PIS subset which includes more than one parallel input stream, to generate a corresponding grouped input stream, each grouped input stream thereby being associated with one of the PIS subsets;
• d. a data memory, wherein the data selector populates the data memory by storing data from each grouped input stream in a separate row of memory, in the order in which the data occurs within the grouped input stream;
• e. means for generating at least one grouped output stream, each grouped output stream including data from at least two of the parallel input streams;
• and
• f. means for demultiplexing each grouped output stream to generate a subset of parallel output streams, thereby associating each output shift register with one of the grouped output streams.