Abstract: Described is a method and apparatus which calculates Cyclic Redundant Check (CRC) for an entity from partial CRCs associated with segments of the entity. The entity includes a data packet segmented into a plurality of Asynchronous Transfer Mode (ATM) cells. The Packet CRC is calculated from the algorithm (A.sub.1 C.sub.1 +A.sub.2 C.sub.2 . . . +A.sub.N C.sub.N)/P with A.sub.i, i=1, . . . , N, representing a partial CRC associated with a particular ATM cell, C.sub.i, i-1, . . . , N, representing a Fixed Remainder and P is the CRC generation polynomial. The C.sub.i values are calculated and stored in a table. The partial CRCs (i.e., A.sub.i 's) are calculated by hardware generator and forwarded to a processor which selects the corresponding value of C.sub.i from the table and generates the CRC for the frame.

Abstract: A communication adapter connected between a communication line and a host processor segments a received data frame by storing the received data in a buffer chain made up of equal length buffers. As each buffer is filled, the adapter interrupts the host. The host moves the data stored in the filled buffer into its own storage. It interrupts the adapter so that the buffer can be returned to the chain of free buffer and completes transmission protocol processing before the entire frame is received. If the frame has been received without error or buffer overrun it is delivered to the user immediately after transfer of the last buffer.