xers. 2.8.1 Bandsplitter Synchronous transmissions with error correction/detection can share the bandwidth of a composite link with the input/output of a sta- tistical multiplexer via a bandsplitter. The bandsplitter is simply a bit-interleaved TDM that splits the bandwidth of the composite link into separate time-slots assigned to each of the synchronous channels and the statistical multiplexer. This arrangement minimizes delay time for the synchronous channels, but reduces bandwidth assigned to the statistical multiplexer. Since maximum data rate over a line is proportional to bandwidth, a reduction in bandwidth reduces the composite link data rate of the device. Applications with moderate to heavy channel loading will fill the multiplexer buffer quicker and more frequently, engaging flow control more frequently to interrupt transmission, resulting in performance degradation. Furthermore, time-slots assigned to the synchronous bandsplitter channels are empty during periods of inactivity, which also reduces communica- tions efficiency. Bandsplitters are useful only when the traffic load- ing of the statistical multiplexer is not seriously effected. PROTOCOLS AND CODES 3.1 WHAT IS A PROTOCOL? Just as protocols are needed for an orderly society, data networks require their own set of rules to ensure the smooth exchange of in- formation between communicating equipments. As data networks grow in complexity, SO too will software provided communications protocols take on added importance. Until now, most of the atten- tion surrounding protocols has focused on the so-called line control procedures, or data link protocols, which provide the rules by which two or more machines may converse, or exchange information, over a data link in an efficient and reliable manner. Minimally, the pro- tocol must offer a means of identifying the sender and receiver on a multipoint or dial-up network, plus a way to indicate the start and end of the information being transmitted, and a method for de- tecting errors and initiating a corre