Abstract: An apparatus and method for multicasting messages stored in data buffers of a data storage. Each message is composed of data stored in a plurality of the data buffers. Each data buffer is controlled and mapped to a unique direct control block (DCB) which stores information characterizing the data buffer. By chaining the DCBs variable length, messages can be generated. Indirect control blocks (ICB) stores information characterizing the data or messages duplicated and points to a DCB. A field in the DCB carries a count representing the number of times the message is to be duplicated.

Abstract: An apparatus and method for multicasting messages stored in data buffers of a data storage. Each message is composed of data stored in a plurality of the data buffers. Each data buffer is controlled and mapped to a unique direct control block (DCB) which stores information characterizing the data buffer. By chaining the DCBs variable length, messages can be generated. Indirect control blocks (ICB) stores information characterizing the data or messages duplicated and points to a DCB. A field in the DCB carries a count representing the number of times the message is to be duplicated.

Abstract: In a packet switched communications system an incoming real-time packet is imbedded after the next block of data of the non-real-time packet being transmitted. This object is accomplished by transmitting each packet along with at least a 1-byte trailer which is used to indicate the packet type, whether the current block of non real time data is preempted or whether the current block of non real time data is resumed.

Abstract: An arbitration method and device for a data processing system wherein N units share a common resource, to allocate the shared resource to a given unit selected from a number of units requesting access thereto.An age value is assigned to each unit and corresponds to the age of the request that will be made by the unit. During an arbitration cycle, a unit whose request will be serviced, if the shared resource becomes available, is selected, this unit being the one whose request has an age value corresponding to the oldest request. Then, the age value associated with each unit is updated when the resource is available, the age of the selected unit assuming a value corresponding to that of the most recent request, the ages of the units not selected that correspond to requests more recent than the one made by the selected unit being increased by a given quantity, and the ages of the units not selected that correspond to requests older than the one made by the selected unit remaining unchanged.