computerarchitecture

Computer architecture is the design and organization of the components that constitute a computer system, including the hardware organization, instruction set architecture (ISA), data paths, memory hierarchy, input/output mechanisms, and control logic. It concerns what a machine can do and how efficiently it can do it, balancing performance, power consumption, manufacturing cost, and programmability. Abstraction levels include the ISA, which defines the programmer-visible state and instructions; the microarchitecture, which implements the ISA in circuitry; and the physical implementation.

Instruction set architecture defines the machine's instructions, data types, addressing modes, registers, and binary encoding. Examples include x86-64, ARM, and RISC-V. Microarchitecture specifies how those instructions are executed, through features such as pipelining, out-of-order execution, branch prediction, caches, and simultaneous multithreading. The memory hierarchy organizes fast, small storage (registers and L1/L2/L3 caches) close to the CPU, then main memory and storage. Input/output and interconnects describe how components communicate (buses, PCIe, memory controllers, network fabrics).

Modern systems rely on parallelism at multiple levels: instruction-level parallelism within a core, thread-level parallelism across cores, and data-level parallelism in vector units and specialized accelerators. Heterogeneous architectures mix general-purpose cores with graphics processors, digital signal processors, or AI accelerators to optimize specific workloads. Design goals include peak performance, energy efficiency, cost, thermal limits, and reliability, often requiring trade-offs across these criteria.

Assessment relies on benchmarks and metrics such as instructions per cycle, FLOPS, memory bandwidth, and latency. The field has evolved from early von Neumann and Harvard designs to multicore processors and domain-specific accelerators. Ongoing research addresses security, parallel programming models, memory technologies, and scalable interconnects for cloud, mobile, and edge computing.