the same memory sizes and data word widths however embodiments with different memory sizes are also feasible as long as for example one size is an integer multiple of the other referring now to fig3 a simplified functional diagram illustrating the memory interface between two data transfer systems 110 120 according to the present invention multiple memory modules are illustrated memory modules 1 through n make up a memory structure 105 of the first data transfer system 110 similarly another set of memory modules 1 through n make up a memory structure 115 of the second data transfer system 120 the interfaces of all of the module pairs 1 through n make up the interface 125 between the two memory structures 105 115 of their respective data transfer systems 110 120 for the structures 105 115 having the same memory sizes and data word widths the data lines are connected directly for every module pair 1 through n address lines for the module pairs 1 through n are connected accessed and controlled by a port b controller data transfers may occur between the module pairs 1 through n in a parallel i e module to module manner without the aid of the cpu of the system alternatively they can also occur between a selected set of module pairs according to their physical addresses or via a logical address mapped memory region such as the cases of a ram drive or a flash drive data being transferred are written in a way that would allow the system in which it resides to decipher the data.