A digital counter allows the provision of start and stop values in order
to allow it to be configurable to any length. The counter rolls over to
zero at a maximum value and proceeds to count until it reaches an
indicated stop count. At that point, it proceeds to the start count and
continues counting. The counter counts half bytes of a cell of data for
transmission to and from a multiport DRAM in accordance with
communication protocols, such as asynchronous transfer mode (ATM.)