1-bit computing: Difference between revisions

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{{Use list-defined references|date=June 2022}}

{{Computer architecture bit widths}}

[[File:MC14500BCP.jpg|thumb|1-bit [[programmable logic controller]] [[Motorola MC14500B|MC14500BCP]]]]

In [[computer architecture]], '''1-bit''' [[integer (computer science)|integer]]s or other [[Data (computing)|data]] units are those that are {{nowrap|1 [[bit]]}} (1/8 [[octet (computing)|octet]]) wide. Also, 1-bit [[central processing unit]] (CPU) and [[arithmetic logic unit]] (ALU) architectures are those that are based on [[processor register|register]]s of that size.

There are no computers or [[microcontroller]]s of any kind that are exclusively 1-bit for all registers and [[address bus]]es. A 1-bit register can only store 2¹two different values, i.e. 0 or 1 (off or on, respectively). This is very restrictive and therefore not enough for a [[program counter]] which, on modern systems, is implemented in an on-chip register, thatbut isn'tis not implemented on-chip in some 1-bit systems. [[Opcode]]s for at least one 1-bit processor architecture were 4-bit and the address bus was 8-bit.

While 1-bit computing is mostly obsolete, [[serial communication|1-bit communication]], then called [[serial communication|serial]] and also 2- or 4-bit communication is still used in modern computers, that are otherwise e.g. 64-bit, and thus also have much larger buses.

While 1-bit CPUs are obsolete, the first (research) [[carbon nanotube computer]] from 2013 is a 1-bit [[one-instruction set computer]] (and has only 178 transistors; since it has only one instruction<!-- SUBNEG (subtract and branch if negative) --> though it can emulate 20 [[MIPS architecture|MIPS]] instructions).<ref name="Courtland_2013"/>

== 1-bit ==

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Other examples of 1-bit architectures are [[programmable logic controller]]s (PLCs), programmed in [[instruction list]] (IL).

Such as the 1969 [[PDP-14]].<ref name=CHD>

{{cite web |url=http://www.chdickman.com/pdp14 |title=DEC PDP-14 Industrial Controller}}

</ref>

Several early [[massively parallel]] computers used 1-bit architectures for the processors as well. Examples include the May 1983 [[Goodyear MPP]] and the 1985 [[Connection Machine]]. By using a 1-bit architecture for the individual processors a very large array (e.g. the Connection Machine had 65,536 processors) could be constructed with the chip technology available at the time. In this case the slow computation of a 1-bit processor was traded off against the large number of processors.

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* [[Bit slicing]]

* [[Turing machine]]

* [[LowEnhanced PinSerial CountPeripheral Interface]] for(eSPI) allows 41-bit communication

** It's successor for modern computers, Intel's [[Enhanced Serial Peripheral Interface]] (eSPI) allows 1-bit, 2-bit, or 4-bit communication

== References ==

{{reflist|refs=

<ref name="Courtland_2013">{{cite web |title=First Computer Made From Carbon Nanotubes Debuts - The modest 1-bit, 1 kHz machine could usher in a new post-silicon era |author-first=Rachel |author-last=Courtland |date=2013-09-25 |website=IEEE Spectrum: Technology, Engineering, and Science News |url=https://spectrum.ieee.org/tech-talk/semiconductors/devices/first-computer-made-from-carbon-nanotubes-debuts |access-date=2021-04-18 |url-status=live |archive-url=https://web.archive.org/web/20220615190932/https://spectrum.ieee.org/first-computer-made-from-carbon-nanotubes-debuts |archive-date=2022-06-15}}</ref>

<ref name="DEC_1969">{{cite book |title=PDP-8/S Maintenance Manual |chapter=III. System Logic - 3.4. Control Circuits - 3.4.1 Adder |date=August 1969 |orig-date=October 1967 |edition=4th printing |publisher=[[Digital Equipment Corporation]] |___location=Maynard, Massachusetts, US |id=F-87S |pages=3-14–3-15 |url=http://www.bitsavers.org/pdf/dec/pdp8/pdp8s/PDP8S_MaintMan.pdf |access-date=2022-06-15 |url-status=live |archive-url=https://web.archive.org/web/20211023025507/http://www.bitsavers.org/pdf/dec/pdp8/pdp8s/PDP8S_MaintMan.pdf |archive-date=2021-10-23}} (191 pages)</ref>

<ref name="Koblentz_2004">{{cite interview |title=LED calculators rule her house |interviewer-first=Evan |interviewer-last=Koblentz |author-first=Katie<!-- aka Kathie / Katherine / Ken --> |author-last=Wasserman |author-link=Ken Wasserman |journal=Computer Collector Newsletter / Technology Rewind |orig-date=January 2004 |date=March 2006 |url=http://www.snarc.net/tr/katie-led.htm |access-date=2017-05-20 |url-status=live |archive-url=https://archive.today/20191227180243/http://www.snarc.net/tr/katie-led.htm |archive-date=2019-12-27 |quote=Probably my most favorite is the Wang 500. It's got several unique things about it: a very unusual ROM memory made of hundreds of long enamel-coated wires wrapped around iron cores; a super-fast single-bit CPU built out of SSI logic chips; and of course tons of really cool-looking colorful keys.}}</ref>

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<ref name="Battle_2010">{{cite web |title=Wang 1200 - Wang WP History |author-first=Jim |author-last=Battle |date=2010-03-07 |url=http://www.wang1200.org/history.html |access-date=2017-05-21 |url-status=live |archive-url=https://web.archive.org/web/20170521004512/http://www.wang1200.org/history.html |archive-date=2017-05-21}}</ref>

<ref name="Motorola_1977_MC14500B">{{cite book |title=Motorola MC14500B Industrial Control Unit Handbook - Theory and Operation of a CMOS one-bit processor compatible with B series CMOS devices |author-first1=Vern |author-last1=Gregory |author-first2=Brian |author-last2=Dellande |author-first3=Ray |author-last3=DiSilvestro |author-first4=Terry |author-last4=Malarkey |author-first5=Phil |author-last5=Smith |author-first6=Mike |author-last6=Hadley |publisher=[[Motorola Semiconductor Products Inc.]] |date=1977 |id=33-B78/8.0 |url=http://tinymicros.com/mediawiki/images/e/ec/MC14500B_Handbook.pdf |access-date=2017-05-20 |url-status=live |archive-url=https://web.archive.org/web/20220401141059/https://tinymicros.com/mediawiki/images/e/ec/MC14500B_Handbook.pdf |archive-date=2022-04-01}} (NB. Also available in German language under the title "Motorola MC14500B Industrial Control Unit Handbuch - Theorie und Anwendung eines Ein-Bit-CMOS-Prozessors".)</ref>

<ref name="Motorola_1995_MC14500B">{{cite book |titlechapter=Industrial Control Unit MC14500B |series=Semiconductor Technical Data |worktitle=Motorola CMOS Logic Data |publisher=[[Motorola]] |edition=revision 3 |date=1995<!-- |orig-date=1/94? --> |pages=306–313 |url=http://www.brouhaha.com/~eric/retrocomputing/motorola/mc14500b/mc14500brev3.pdf |access-date=2012-08-01 |url-status=live |archive-url=https://web.archive.org/web/20170520123638/http://www.brouhaha.com/~eric/retrocomputing/motorola/mc14500b/mc14500brev3.pdf |archive-date=2017-05-20}}</ref>

<ref name="Ludwig_1986_WDR-1">{{cite book |title=Fast alles über den WDR-1-Bit-Computer |language=de |author-first1=Volker |author-last1=Ludwig |author-first2=Klaus |author-last2=Paschenda |author-first3=Heinz |author-last3=Schepers |author-first4=Hermann-Josef |author-last4=Terglane |author-first5=Klaus |author-last5=Grannemann |author-first6=Burkhard |author-last6=John |author-first7=Hermann |author-last7=Komar |author-first8=Ludwig |author-last8=Meinersen |publisher=DATANorf |___location=Neuss & Recklinghausen, Germany |date=1986 |url=http://wdr-1-bit-computer.talentraspel.de/documents/wdr_1-40.pdf |access-date=2017-05-20 |url-status=live |archive-url=https://web.archive.org/web/20170520131325/http://wdr-1-bit-computer.talentraspel.de/documents/wdr_1-40.pdf |archive-date=2017-05-20}}</ref>

<ref name="Digipart_2022">{{cite web |title=MC14500B Price & Stock |website=www.digipart.com |url=https://www.digipart.com/part/mc14500b?gclid=EAIaIQobChMIy8i09b7R5QIVT0HTCh1YgQZzEAEYAiAAEgJza_D_BwE |access-date=2021-03-29 |url-status=live |archive-url=https://web.archive.org/web/20220615184147/https://www.digipart.com/part/mc14500b |archive-date=2022-06-15}}</ref>