48-bit

1 4 8 12 16 18 24 26 31 32 36 48 60 64 128 256 512

16 32 64

×½ ×1 ×2 ×4 ×8

32 64 128

In computer architecture, 48-bit integers can represent every integer from 0 inclusive through 256 tera (2⁴⁸ = 2.814749767×10¹⁴) bytes exclusive. A 48-bit memory address can directly address every byte of 256 terabytes of storage. 48-bit can refer to any other data unit that consumes 48 bits (6 octets) in width. Examples include 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 the AN/FSQ-32, CDC 1604/upper-3000 series, BESM-6, Ferranti Atlas, and Burroughs large systems (B5xxx-B8xxx, most of which additionally had a 3- or 4-bit type tag).

The IBM System/38 and the AS/400, in its CISC variants, are 48-bit addressing systems. The address size used in logical block addressing was increased to 48 bits with the introduction of ATA-6. The Ext4 file system physically limits the file block count to 48 bits.

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