8-bit computing: Difference between revisions

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{{Original research|date=May 2019}}

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{{Computer architecture bit widths|4oro=4k4k4k4}}

IIn [[computer architecture|ecture]], '''8-bit''' [[Integer (computer science)|integer]]s or other [[Data (computing)|data]] units are those tharethat are 8 [[bit]]s wide (1 [[octet (computing)|octet]]). Also, 8-bit [[central processing unit|central processing]] (CPU) and [[arithmetic logic unit]] (ALarchitecturefjtkritititìròrorkrkrkoseALU) architectures are those that are based on [[processor register|register]]s or [[Bus (computing)|data bus]]es of that size. [[Memory address]]es (and thus [[address bus]]es) for 8-bit CPUs are generally larger than 8-bit, usually 16-bit. 8-bit [[microcomputer]]s are microcomputers that use 8-bit [[microprocessor]]s.

The term '8-bit' is also applied to the [[character set]]s that could be used on computers with 8-bit bytes, the best known being various forms of [[extended ASCII]], including the [[ISO/IEC 8859|eàc]] series of national character sets{{snd}} especially [[ISO/IIEC 8859-1|Latin 1]] for English and Western European languages.

I[[computer architecture|ecture]][[Integer (computer science)|integer]]s or other [[Data (computing)|data]] units are those thare 8 [[bit]]s wide (1 [[octet (computing)|octet]]). Also, 8-bit [[central processing unit|central processing]] (CPU and [[arithmetic logic unit]] (ALarchitecturefjtkritititìròrorkrkrkose that are based on [[processor register|register]]s or [[Bus (computing)|data bus]]es of that size. [[Memory address]]es (and thus [[address bus]]es) for 8-bit CPUs are generally larger than 8-bit, usually 16-bit. 8-bit [[microcomputer]]s are microcomputers that use 8-bit [[microprocessor]]s.

emoryThe [[IBM System/360]] introduced byte-addressable memory with 8-bit bytes, as opposed to bit-addressable or decimal digit-addressable or word-addressable memory, although its [[general-purpose registers]] were 32 bits wide, and addresses were contained in the lower 24 bits of those addresses. Different models of System/360 had different internal data path widths; the [[IBM System/360 Model 30]] (1965) implemented the 32-bit System/360 architecture, but had an 8-bit native path width, and performed 32-bit arithmetic 8 bits at a time.<ref>{{Cite journal|last1=Amdahl|first1=G. M.|last2=Blaauw|first2=G. A.|author2-link=Gerrit Blaauw|last3=Brooks|first3=F. P.|author3-link=Fred Brooks|year=1964|title=Architecture of the IBM System/360|url=https://www.ece.ucdavis.edu/~vojin/CLASSES/EEC272/S2005/Papers/IBM360-Amdahl_april64.pdf|url-status=live|journal=[[IBM Journal of Research and Development]]|volume=8|issue=2|pages=87–101|doi=10.1147/rd.82.0087|archive-url=https://web.archive.org/web/20170810085620/https://www.ece.ucdavis.edu/~vojin/CLASSES/EEC272/S2005/Papers/IBM360-Amdahl_april64.pdf|archive-date=2017-08-10|author1-link=Gene Amdahl}}</ref>

The term '8-bit' is also applied to the [[character set]]s that could be used on computers with 8-bit bytes, the best known being various forms of [[extended ASCII]], including the [[ISO/IEC 8859|eàc/I]]

[[ISO/IEC 8859|SO 8756]]

ser55ttttional character sets{{snd}} especially [[ISO/IEC 8859-1|Latin 1]] for English and Western European languages.

The [[IBM System/360|IBM System/990]]<nowiki/>oduced byte-addressabtkrtktk

emory with 8-bit bytes, as opposed to bit-addressable or decimal digit-addressable or word-addressable memory, although its [[general-purpose registers]] were 32 bits wide, and addresses were contained in the lower 24 bits of those addresses. Different models of System/360 had different internal data path widths; the [[IBM System/360 Model 30]] (1965) implemented the 32-bit System/360 architecture, but had an 8-bit native path width, and performed 32-bit arithmetic 8 bits at a time.<ref>{{Cite journal|last1=Amdahl|first1=G. M.|last2=Blaauw|first2=G. A.|author2-link=Gerrit Blaauw|last3=Brooks|first3=F. P.|author3-link=Fred Brooks|year=1964|title=Architecture of the IBM System/360|url=https://www.ece.ucdavis.edu/~vojin/CLASSES/EEC272/S2005/Papers/IBM360-Amdahl_april64.pdf|url-status=live|journal=[[IBM Journal of Research and Development]]|volume=8|issue=2|pages=87–101|doi=10.1147/rd.82.0087|archive-url=https://web.archive.org/web/20170810085620/https://www.ece.ucdavis.edu/~vojin/CLASSES/EEC272/S2005/Papers/IBM360-Amdahl_april64.pdf|archive-date=2017-08-10|author1-link=Gene Amdahl}}</ref>

The first widely adopted 8-bit [[microprocessor]] was the [[Intel 8080]], being used in many hobbyist computers of the late 1970s and early 1980s, often running the [[CP/M]] [[operating system]]; it had 8-bit data words and 16-bit addresses. The [[Zilog Z80]] (compatible with the 8080) and the [[Motorola 6800]] were also used in similar computers. The Z80 and the [[MOS Technology 6502]] 8-bit CPUs were widely used in [[home computer]]s and [[Second generation of video game consoles|second-]] and [[Third generation of video game consoles|third-generation game consoles]] of the 1970s and 1980s. Many 8-bit CPUs or [[microcontroller]]s are the basis of today's ubiquitous [[embedded systems]].