4-bit computing: Difference between revisions

Revision as of 10:50, 13 April 2023

Revision as of 10:51, 13 April 2023

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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>

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 50&nbsp;g50g --> (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. -->

In addition, some early calculators{{snd}} such as the 1967 [[Casio AL-1000]], the 1972 [[Sinclair Executive]], and the aforementioned 1984 [[HP Saturn]]{{snd}} had 4-bit [[datapath]]s that accessed their registers 4 bits (one BCD digit) at a time.<ref>[http://www.vintagecalculators.com/html/casio_al-1000.html "Desk Electronic Calculators: Casio AL-1000"]</ref>