Von Neumann architecture

A computer design in which instructions and data share the same memory and communication pathways, typically under the control of a central processor.

Stored-program computer: A computer whose instructions are stored in memory and can be treated as data. The architecture implements the stored-program idea by keeping instructions and data in shared memory.
EDVAC: An early electronic stored-program computer developed in the United States after World War II. Its design helped put shared instruction-and-data memory into practice.
Instruction set architecture: The specification of a processor’s instructions, registers, data types, and machine-visible behavior. It defines the instructions the central processor fetches from memory.
Harvard architecture: A computer design with separate memories and pathways for instructions and data. It avoids the shared instruction-and-data pathway characteristic of this architecture.
Self-modifying code: A program that changes its own instructions while it runs. When instructions and data share memory, code can be addressed and altered as data.
Central processing unit: The processor that fetches and executes instructions and coordinates a computer’s operations. It executes instructions fetched from the shared memory.
First Draft of a Report on the EDVAC: John von Neumann’s 1945 report describing the logical design of the EDVAC. The report became a foundational statement of the architecture associated with von Neumann.
Machine code: The binary instructions a processor executes directly. In a stored-program design, machine code resides in memory alongside data.
Modified Harvard architecture: A design that combines a unified memory view with separate instruction and data caches or pathways. Many processors blend shared main memory with separate high-speed instruction and data access.
Executable space protection: A security mechanism that marks memory regions as non-executable to limit code execution attacks. Shared instruction and data memory makes permissions for writable code especially consequential.

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