View source for 48-bit

{{Computer architecture bit widths}}
In computer&nbsp;architecture, '''48-bit''' [[Integer (computer science)|integer]]s can represent 281,474,976,710,656 (2<sup>48</sup> or 2.814749767×10<sup>14</sup>) discrete values. This allows an unsigned binary integer range of 0 through 281,474,976,710,655 (2<sup>48</sup> − 1) or a [[Signed number representations|signed]] [[Two's complement|two's complement]] range of -140,737,488,355,328 (-2<sup>47</sup>) through 140,737,488,355,327 (2<sup>47</sup> − 1). A 48'''-bit''' [[Memory address|memory address]] can directly address every byte of 256 [[Tebibyte|tebibytes]] of storage. 48'''-bit''' can refer to any other [[Data#Uses of data in computing|data]] unit that consumes 48 [[Bit|bit]]s (6 [[Octet (computing)|octets]]) in width.  Examples include 48-bit [[Central processing unit|CPU]] and [[Arithmetic logic unit|ALU]] [[Computer architecture|architecture]]s are those that are based on [[Processor register|register]]s, [[Engineering:Address bus|address bus]]es, or [[Engineering:Bus (computing)|data bus]]es of that size.

==Word size==
Computers with 48-bit words include the AN/FSQ-32, [[Company:Control Data Corporation|CDC]] 1604/upper-3000 series, [[BESM#BESM-6|BESM-6]], [[Company:Ferranti|Ferranti]] [[Engineering:Atlas (computer)|Atlas]], and [[Burroughs large systems]] (B5xxx-B8xxx, most of which additionally had a 3- or 4-bit type tag).

==Addressing==
The IBM System/38 and the AS/400, in its [[Complex instruction set computer|CISC]] variants, are 48-bit addressing systems. The address size used in [[Logical block addressing|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.

The minimal implementation of the [[X86-64|x86-64]] architecture provides 48-bit addressing encoded into 64 bits; future versions of the architecture can expand this without breaking properly written applications.

The media access control address ([[MAC address]]) of a computer uses a 48-bit address space. This can be changed to 64-bit addressing.

==Images==
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|date=June 2013}} 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 [[Colour banding|banding]] or [[Posterization|posterization]].

{{CPU technologies}}

[[Category:Data unit]]

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