48-bit Computing

48-bit Computing

In computer architecture, 48-bit integers, memory addresses, or other data units are those that are 48 bits (6 octets) wide. Also, 48-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size.

Computers with 48-bit words include CDC 1604 and BESM-6.

The IBM AS/400, in its CISC variants, is a 48-bit addressing system. The address size used in logical block addressing was increased to 48 bits with the introduction of ATA-6.

The minimal implementation of the x86-64 architecture provides 48-bit addressing encoded into 64 bits; future versions of the architecture can expand this without breaking properly written applications.