Data transfer system for multiple network processors using dual DRAM storage

A method of storing and moving data for use by a network processor comprising the steps of:

• a) storing the data in first and second DDR DRAM chips working in parallel and having synchronized clocks;
• b) establishing a data movement pattern comprising a predetermined number of cycles in each repeating cell of the DDR DRAM clocks;
• c) dedicating a contiguous group of cycles in the pattern to full ‘read’ during a ‘read’ window;
• and
• d) dedicating a second contiguous group of cycles in the pattern to fill ‘write’ during a ‘write’ window.

An arbitration method for a network processor for providing a high bandwidth movement of data for multiple frames being serviced by the network processor irrespective of frame size, comprising the steps of:

• a) establishing time slots for reading each of the banks a, b, c, and d in a DRAM chip, and separate time slots for writing each of the banks a, b, c and d;
• b) determining which of the banks need to be read and which of the banks need to be written for a given frame;
• c) accessing only the banks that are required by said given frame;
• d) reviewing all frames needing ‘read’ access during each time slot;
• e) arbitrating for all ‘a’ banks between all frames needing ‘read’ access to the ‘a’ banks;
• and
• f) sequentially arbitrating for all ‘b’, ‘c’, and ‘d’ banks for a frame requiring access to the ‘b’, ‘c’, and ‘d’ banks.

A method of providing a network processor with random ‘read’ and ‘write’ access to a plurality of banks a, b, c and d of a DRAM chip comprising the steps of:

• a) during a ‘read’ window, arbitrating to give priority to bank ‘a’ for any ‘read’ commands that need to be fulfilled;
• b) if no ‘read’ access is available from a bank ‘a’, giving bank ‘a’ access to a ‘write’ command, and
• b1) giving the ‘write’ access to the next bank ‘b’;
• c) if bank ‘b’ access is different than the access of bank ‘a’, bypassing bank ‘b’ and giving access to bank ‘c’;
• and
• d) modifying arbitration to give priority to bank ‘c’ regardless of whether it is ‘read’ or ‘write’.