Abstract: A local area network comprising a plurality of terminals interconnected by a communication bus is disclosed. Each terminal comprises a memory, a main processor, and a co-processor. To transmit information in a communication mode, the main processor loads data into a transmit buffer area of the memory, and the co-processor reads the data from the transmit buffer area and transmits a packet on the communication bus. Similarly, the co-processor receives data from the communication bus and stores it in a receive buffer area from which it is read by the main processor for use. In an alternative mode, called the direct transfer mode, the co-processors are reconfigured so that data for transmission is read from the actual locations in memory where it is stored (not the transmit buffer area), and received data is stored in storage areas where it is expected to be used (not the receive buffer area).

Abstract: In a telecommunication switching system adapted for handling call signaling information and data in packet format, a number of protocol handlers (150) are interconnected by means of a local area network (171,173). A variable number of spares may be available for each group of protocol handlers as defined by a ratio table (400) stored in the memory of the systems control processor (100). The ratio table may be changed from time to time to redefine the ratio of spares to actives for each group. In response to a request to activate an additional protocol handler in a group, the ratio table is consulted and an error message is generated if the activation of an additional protocol handler causes the specified ratio to be exceeded.