4-bit computing: Difference between revisions

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'''4-bit computing''' is the use of [[computer architecture]]s in which [[integer (computer science)|integers]] and other [[data (computer science)|data]] units are 4 [[bit]]s wide. 4-bit [[central processing unit]] (CPU) and [[arithmetic logic unit]] (ALU) architectures are those that are based on [[processor register|registers]] or [[bus (computing)|data buses]] of that size. A group of four bits is also called a [[nibble]] and has 2⁴ = 16 possible values, with a range of 0 to 15.

4-bit computation is obsolete, i.e. CPUs supporting 4-bit as the maximum size. However, 4-bit integers (or smaller), and 4-bit floating point is gaining ground for AI, large-language models.<ref>{{Citationcite conference |lastarxiv=Liu2310.16836 |firstdoi=Shih10.18653/v1/2023.emnlp-yangmain.39 |title=LLM-FP4: 4-Bit Floating-Point Quantized Transformers |datebook-title=Proceedings of the 2023-10-25 |url=https://arxiv.org/abs/2310.16836Conference on Empirical Methods in Natural Language Processing |access-date=2025-03-302023 |publisherlast1=arXivLiu |doifirst1=10.48550/arXiv.2310.16836 |id=arXiv:2310.16836Shih-Yang |last2=Liu |first2=Zechun |last3=Huang |first3=Xijie |last4=Dong |first4=Pingcheng |last5=Cheng |first5=Kwang-Ting |pages=592–605 }}</ref>

4-bit processors were widely used in [[electronic calculator]]s and other roles where decimal math was used, like electronic [[cash register]]s, [[microwave oven]] timers, and so forth. This is because a 4-bit value holds a single [[binary-coded decimal]] (BCD) digit, making it a natural size for directly processing decimal values. As a 4-bit value is generally too small to hold a [[memory address]] for real-world programs or data, the [[address bus]] of these systems was generally larger. For instance, the canonical 4-bit [[microprocessor]], the [[Intel 4004]], had a 12-bit address format.

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== References ==

{{refsreflist|refs=

<ref name="Mack_2005">{{cite web |title=The Microcomputer Revolution |author-first=Pamela E. |author-last=Mack |date=2005-11-30 |url=http://www.clemson.edu/caah/history/FacultyPages/PamMack/lec122/micro.htm |access-date=2009-12-23}}</ref>

<ref name="Hofstra_History">{{cite web |title=History in the Computing Curriculum |url=http://www.hofstra.edu/pdf/comphist_9812tla6.pdf |access-date=2017-06-22 |archive-url=https://web.archive.org/web/20110719211222/http://www.hofstra.edu/pdf/CompHist_9812tla6.PDF |archive-date=2011-07-19 |url-status=dead}}</ref>

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{{CPU technologies}}

[[Category:Data unit]]