byteaddressed

Byteaddressed, also written as byte-addressed, memory is a memory addressing scheme in which the unit of addressability is the memory byte. In byte-addressable systems, every individual byte has a unique address, and consecutive memory locations are addressed one byte apart. This is in contrast to word-addressable systems, where the smallest addressable unit is a word (a fixed number of bytes). The term reflects the granularity at which software can directly read and write data.

Most modern general‑purpose CPUs and systems use byte-addressable memory. Architectures such as x86, ARM, PowerPC, MIPS, and RISC-V treat bytes as the fundamental addressing unit, enabling fine-grained access to data of varying sizes. This design simplifies programming and compiler implementation, since languages can rely on a single-addressable unit for basic data and rely on higher‑level abstractions for larger types. The C language, for example, assumes a byte as the basic unit of addressable memory and defines pointer arithmetic in terms of bytes.

Key implications include the size of the address space and the width of the address bus. With n-bit addresses, a system can address up to 2^n bytes of memory (e.g., 2^32 bytes for a 32-bit address space, about 4 GiB; 2^64 bytes for a 64-bit space, about 16 exbibytes). Memory organization also interacts with data alignment and endianness: while addressing is by bytes, multi-byte values may require alignment for performance or correctness, and the order of bytes within larger values (endianness) affects interpretation of multi-byte data.

Historically, some early systems used word-addressing, but byte-addressable memory has become the standard in contemporary computing.