48-bit

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Bit
1 4 8 12 16 18 24 26 31 32 36 48 60 64 128 256 512
Application
16 32 64
Floating point precision
×½ ×1 ×2 ×4
Floating point decimal precision
32 64 128

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.

Word size[edit]

Computers with 48-bit words include the AN/FSQ-32, CDC 1604/CDC 3xxx, BESM-6, and Burroughs large systems (B5xxx-B8xxx, which additionally had a 3-4 type tag).

Addressing[edit]

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 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.

Images[edit]

In digital images, 48 bits per pixel, or 16 bits per each color channel (red, green and blue), is used for accurate processing. For the human eye, it is almost impossible to see any difference between such an image and a 24-bit image[citation needed], but the existence of more shades of each of the three primary colors (65,536 as opposed to 256) means that more operations can be performed on the image without risk of noticeable banding or posterization.