4-bit computing: Difference between revisions

Revision as of 15:31, 3 April 2023

Revision as of 15:37, 3 April 2023

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{{Short description|Computer architecture bit width}}

{{Use dmy dates|date=February 2020|cs1-dates=y}}

{{Computer architecture bit widths}}

'''4-bit computing''' refers to In [[computer architecture]],s '''4-bit'''in which [[Integerinteger (computer science)|integer]]s, orand other [[data (computer science)|data]] units are those that are 4 [[bit]]s wide. Also, 4-bit [[central processing unit]] (CPU) and [[arithmetic logic unit]] (ALU) 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 4-bit CPUs are generally much larger than 4-bit (since only 16 memory locations would be very restrictive), such as 12-bit or more, while they could in theory be 8-bit. A group of four bits is also called a [[nibble]] and has 2⁴ = 16 possible values.

A group of four bits is also called a [[nibble]] and has 2⁴ = 16 possible values.

== History ==

[[Filefile:Alps remote control BHR970001B - NEC D63GS-7525.jpg |thumb|alt=20-pin PSOP|NEC D63GS: a 4-bit microcontroller for [[infrared remote control]] transmission]]

[[Filefile:Intel C4004 greytraces CPU.jpg |thumb|alt=left|16-pin DIP| Intel C4004]]

[[Filefile:Olympia CD700 Desktop Calculator. 1971.Microprogrammable Arithmetic Processor System Devices (MAPS).jpg |thumb|alt=card-edge PCB| Olympia CD700 Desktop Calculator using the National Semiconductor MAPS MM570X [[bit-serial]] 4-bit microcontroller]]

[[Filefile:Alps remote control BHR970001B-7517.jpg |thumb|alt=infraredleft|Infrared remote control PCB| an [[infrared remote control]] transmitter controlled by a NEC D63GS 4-bit microcontroller]]

Some of the first [[microprocessor]]s had a 4-bit word length and were developed around 1970. The first commercial microprocessor was the [[binary-coded decimal]] (BCD-based) [[Intel 4004]],<ref name="Mack_2005"/><ref name="Hofstra_History"/> developed for calculator applications in 1971; it had a 4-bit word length, but had 8-bit instructions and 12-bit addresses. It was succeeded by the [[Intel 4040]].

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The [[Zilog Z80]], although it is an 8-bit microprocessor, has a 4-bit ALU.<ref name="Shima_Z80"/><ref name="Shirriff_Z80"/>

Although the [[Data General Nova]] is a series of 16-bit minicomputers, the original Nova and the Nova 1200 internally processed numbers 4 bits at a time with a 4-bit ALU,<ref>{{ cite interview | first = Gardner | last = Hendrie | title = Oral History of Edson (Ed) D. de Castro | date = 22 November 2002 | url = http://archive.computerhistory.org/resources/access/text/2012/07/102702207-05-01-acc.pdf | pp = 44 }}</ref> sometimes called "nybble-serial".<ref>[https://rcsri.org/collection/nova-1200/ "Nova 1200"]</ref>

|first=Gardner |last=Hendrie

|title=Oral History of Edson (Ed) D. de Castro

|date=22 November 2002

|url=http://archive.computerhistory.org/resources/access/text/2012/07/102702207-05-01-acc.pdf

}}

p. 44.

</ref>

sometimes called "nybble-serial".<ref>

[https://rcsri.org/collection/nova-1200/ "Nova 1200"].

</ref>

The [[HP Saturn]] processors, used in many [[Hewlett-Packard]] calculators between 1984<!-- intro of HP-71B --> and 2003<!-- when the HP49 was discontinued and replaced by an ARM based model developed by Kinpo --> <!-- EOL announcement of HP 50g --> (including the [[HP&nbsp;48 series]] of scientific calculators) are "4-bit" (or hybrid 64-/4-bit) machines; as the Intel 4004 did, they string multiple 4-bit words together, e.g. to form a 20-bit memory address, and most of the registers are 64 bits wide, storing 16 4-bit digits.<!-- Its instructions were 10 bits wide.--><!-- The previous statement is factually inaccurate and not supported by the cited sources --><!-- <ref name="HPM">{{cite web |url=http://www.hpmuseum.org/techcpu.htm |title=HP CPU and Programming |access-date=2014-01-14}}</ref> --><!-- This reference is invalid because it points to a page which describes the microarchitectures of the HP41 and older calculators which did not use the Saturn. The reference has been updated to point to the H.P. Saturn specific page. --><ref name="HPM_Saturn"/><ref name="Grack_Saturn"/><ref name="HPCalc_Saturn"/><!--{{Off-topic|date=December 2015|HP Saturn}}Since 2003, new Saturn-based HP calculators{{Dubious |date=December 2015| reason=These are not "Saturn-based" processors. The "Saturn+" isn't even a Saturn processor, but an emulation of one.}} (including the [[HP 49/50 series]]) use a 32-bit processor with an [[ARM920T]] core to emulate an extended Saturn processor architecture named [[HP Saturn+|Saturn+]] at a higher speed. -->

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[[Binary-coded decimal]] is a digital encoding method for numbers using decimal notation, with each decimal digit represented by four bits.

== List of 4-bit processors ==

[[Filefile:National Semiconductor MM5700CA D Microprocessor.jpg |thumb|upright|alt=16-pin DIP| National Semiconductor MM5700CA/D [[bit-serial]] 4-bit microcontroller ]]

[[File:Intel C4004 greytraces CPU.jpg |thumb|alt=16-pin DIP| Intel C4004]]

[[File:Alps remote control BHR970001B-7517.jpg |thumb|alt=infrared remote control PCB| an [[infrared remote control]] transmitter controlled by a NEC D63GS 4-bit microcontroller]]

[[File:Alps remote control BHR970001B - NEC D63GS-7525.jpg |thumb|alt=20-pin PSOP|NEC D63GS: a 4-bit microcontroller for [[infrared remote control]] transmission]]

[[File:Olympia CD700 Desktop Calculator. 1971.Microprogrammable Arithmetic Processor System Devices (MAPS).jpg |thumb|alt=card-edge PCB| Olympia CD700 Desktop Calculator using the National Semiconductor MAPS MM570X [[bit-serial]] 4-bit microcontroller]]

[[File:National Semiconductor MM5700CA D Microprocessor.jpg |thumb|upright|alt=16-pin DIP| National Semiconductor MM5700CA/D [[bit-serial]] 4-bit microcontroller ]]

* [[Intel 4004]] (first 4-bit microprocessor from 1971, though [[Four-Phase Systems]] AL1 from 1969 is older, discontinued 1981)

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* [[Low Pin Count]]

== References ==

{{Reflistrefs|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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}}

== External links ==

* [http://www.hpmuseum.org/saturn.htm Saturn CPU]

* {{cite web |url=http://www.epson.jp/device/semicon_e/product/mcu/high_4bit/ |archive-url=https://web.archive.org/web/20130729191831/http://www.epson.jp/device/semicon_e/product/mcu/high_4bit/ |archive-date=2013-07-29 |website=Epson |title=Products: High Performance 4-bit Microcontrollers (S1C63 family)}}

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{{CPU technologies}}

{{Use dmy dates|date=February 2020|cs1-dates=y}}

[[Category:Data unit]]