Byteaddressable

Byteaddressable is a memory architecture in which the smallest addressable unit of memory is one byte, typically 8 bits. In byteaddressable systems, each memory address identifies a single byte, and multi-byte data occupy consecutive addresses. This contrasts with bit-addressable architectures, where individual bits are addressable, or word-addressable systems, where addresses refer to fixed-size words.

Most contemporary CPUs and memory systems are byteaddressable; pointers and array indices typically count bytes. The size of a data type is measured in bytes, and multi-byte values span adjacent addresses. Endianness determines how the bytes of a multi-byte value are ordered in memory but does not change the address granularity.

The byteaddressable model offers fine-grained memory addressing, which supports compact data structures and straightforward input/output. It simplifies language and compiler design because pointers can be treated as byte addresses, and many languages provide a byte type to access raw memory. However, performance considerations include alignment: multi-byte objects often benefit from alignment to their natural boundaries, and caches and memory fetch units are optimized for aligned accesses.

Historically, some architectures used addressing schemes other than bytes, but byteaddressable memory has become the standard in modern general-purpose computing. The term is commonly discussed in the contexts of computer architecture, programming languages, and memory models, where it underpins how software maps data structures onto physical memory.