Von Neumann architecture

Computer architectures have evolved over the years from the classic von Neumann architecture into a variety of forms. Great benefits to operating speed have accrued. The major contributions to speed have been the introductions of parallel processors and of pipelining. For many years, these innovations were transparent to the programmer. For example, to program in Fortran to run on a CDC 6600 (10, one did not take cognizance of the existence of multiple functional units, nor did one consider the I/O channels when writing Fortran applications for the IBM 360 series (2). This was because the parallel processors were hidden behind appropriate hardware or software. 

Conventional CPUs found in the majority of modern computers, such as those manufactured by Intel and advanced micro devices (AMD), are designed for sequential code execution as per the Von Neumann architecture [16]. While running a program, the CPU fetches instructions and associated data from the computer s random access memory (RAM), decodes it, executes it, and then writes the result back to the RAM. Within the realm of Flynn s taxonomy [17], this would be classified as single instruction, single data (SISD). 

Molecular and supramolecular devices incorporated into ultra-micro-circuits represent potential hardware components of eventual systems that might qualify as molecular computers, whose highly integrated architecture and operation would not be of the von Neumann type. On the biological side, the fabrication of components for sensory and motor protheses could be considered. All these entities may result from the self-assembly of suitably instructed subunits so that computing via self-assembly may be envisaged. 

There are many reasons for this choice, among them the prior existence of control structures, data structures, input/output facilities, and a general von Neumann framework. Further, a preprocessor can be implemented to compile Multilin into the embedding language and a selection of subroutine calls which can be coded specifically for each architecture. 

Opposed to conventional structures of data processing systems this architecture contains multi-port devices. By this we allow implementation of data flow concepts and parallel processing and we avoid the von Neumann bottleneck due to a single link between memory and control/ operation units of classical computing systems. The most important component of the system is a 3-port paged memory which is used ... 

Minicomputers, and computers in general, are already the most complicated devices ever developed. Revolutionary architectures will raise this complexity by many orders of magnitude. Revolutionary architectures will break from the traditional von Neumann model of computer... 

Von Neumann strongly believed that a general theory of computation in complex networks of automata such as cellular automata would be essential both for understanding complex systems in nature and for designing artificial complex systems. Von Neumann made foundational contributions to such a theory, and it is thus ironic that the standard model of computation, with a CPU, globally accessible memory, serial processing, and so on has been dubbed the von Neumann style architecture, and architectures such as cellular automata have been dubbed non-von Neumann style. ... 

---