A computer architecture refers to the structure of the components and to all work and instruction structures concerning the internal data processing. The computer architecture is expressed in terms of computing power and application.
The basic concept of most computer systems can be divided into the three subsystems: Processor, memory and input-output system. In this basic concept, which corresponds to the Von Neumann computer, the processor takes care of the execution of the arithmetic operations, the memory provides the storage space for programs and data, and the input/output system, which is controlled via the processor, takes care of the data storage and the presentation of the results on the display. The units are interconnected via the system bus.
Computers are classified according to certain criteria. The most commonly used classification of computer architectures comes from Michael J. Flynn and is expressed in terms of how processors handle instructions and data streams. Flynn classifies computer architectures in terms of instruction execution into computers where different processors can perform different operations simultaneously, and those computers where the operations of all processors can be applied to the same or to different data sets.