Abstract: A data processing system having a CPU (central processing unit), a system bus and a main memory connected to the system bus, comprises a cache memory connected to the system bus for storing a predetermined part of data stored at the main memory, a first path unit for coupling the CPU with the cache memory, a second path unit for connecting the CPU to the system bus, and controller for enabling one of the first and the second path units. In the data processing system, the main memory is accessed only if a cache miss occurs while the first path unit is enabled, and the main memory and the cache memory are accessed simultaneously while the second path unit is enabled.

Abstract: An apparatus for interfacing a data processing system with a plurality of data communications networks comprises: M number of interfacing units, each for coordinating data exchange between the data processing system and the plurality of data communications networks, wherein each of the M number of interfacing units are identical to each other and operate alternately in an active and a stand-by modes so that one in the M number of interfacing units is in active mode while the others are in stand-by mode and M is a positive integer larger than one; and buses for exchanging data among the M number of interfacing units.

Abstract: An apparatus for interfacing a data processing system with n.times.N number of data communications network(s) includes N number of interface units, a pair of control units, and linking units, both n and N being positive integer, respectively. The interface units coordinate a data exchange between the data communications network(s) and the control unit in response to control signals, wherein each interface unit includes n communications ports. Each in the pair of control units generates the control signals and coordinates a data exchange between the data processing system and the interfacing units, wherein each control unit is identical to each other, operates alternately in active/stand-by mode and shares data by using a path therebetween. The linking unit is for use in exchanging data between the data processing system and the control units, between the control units and the interfacing units, and between the interfacing units and the data communications network(s).