A generic high bandwidth adapter providing a unified architecture for data communications between buses, channels, processors, switch fabrics and/or communication networks. Data is carried by data stream packets of variable lengths, and each packet includes a header control information portion required by communication protocols used to mediate the information exchange, and normally a data portion for the data which is to be communicated. A packet memory stores data packets arriving at a plurality of generic adapter input/output ports. The packet memory is segmented into a plurality of buffers, and each data packet is stored in one or more buffers as required by the length thereof. A generic adapter manager is provided for performing and synchronizing generic adapter management functions, including implementing data structures in the packet memory by organizing data packets in buffers, and organizing data packets into queues for processing by the processor subsystem or transfer to or from generic adapter input/output ports. The generic adapter manager prepares future response to anticipated requests for communications services which are functions of the current requests for communication services, such as preparing a response for an anticipated request for a next buffer by a current request for a receipt of data. The generic adapter manager stores the future responses at specified addresses in memory which can be read by a requester. Each generic adapter input/output port has associated therewith a packet memory interface providing for the transfer of data packets into and out of the packet memory, such that when a data packet is received at an input/output port, the data packet is transferred into the adapter packet memory and queued for processing.