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Skoch3 ( talk) 19:55, 7 January 2010 (UTC)Anthony, Larry, AND I changed the language explaining that all the gates can be constructed from either NAND or NOR gates. We wrote: "All other types of Boolean logic gates (i.e., AND, OR, NOT, XOR, XNOR) can be created from a suitable network of NAND gates. Similarly all gates can be created from a network of NOR gates. Historically, NAND gates were easier to construct from MOS technology and thus NAND gates served as the first pillar of Boolean logic in electronic computation."
NAND and NOR gates in NMOS or CMOS both look equally complex/simple. Are you sure you don't mean TTL, where the multi-emitter input allows NAND gates to be much simpler than NOR gates? 60.241.12.136 ( talk) 11:43, 8 July 2010 (UTC)
The images are for the American standard for gate symbols. The European, which I belive is the real standard (approved by ISO/ANSI or something), standard looks different. An AND gate is a square with an ampersand in it, OR is a square with >= 1 in it and so on. I couldn't find any pics for them though. :-( asdfasdfsdf
The article mentions Nikola Tesla having patented logic gates as US645576, but I looked up that patent, "System of transmission of electrical energy", and it appears to describe a means of transmitting electricity through the air, but nothing to do with logic gates. I've taken the reference to that patent out of the article. -- Arteitle 19:51, Mar 7, 2004 (UTC)
The relevant patents are US 723,188 and US 725,605 granted in 1903. They were filed as one application in July 1900 but subsequently divided. I have added them to the text. Conception of the idea was at least as far back as 1896, '...I have an instinctive knowledge of the same...' Tesla said during the interference deposition for the patent, (US Patent Office Interference No 21,701, Systems of Signaling, Nikola Tesla vs. Reginald A. Fessenden, 1902, reply to question 9, August 5th 1902)-- Smark33021 21:32, 23 Dec 2004 (UTC)
I'm new here, so I don't want to make any changes. I shall note, however, that logic gates used in digital integrated circuitry do not operate in this manner. The author is conveying the idea that a logic gate either allows a signal to pass (in his diagram from left to right) or doesn't allow a signal to pass. While this seems sensible to the novice, it is not correct.
The reason that the author's conception of logic gate cannot be used in digital circuitry is that when a signal is not allowed to pass--for instance, if one transistor in his AND gate is OFF--the signal (technically the voltage level) on the OUT end of his logic gate is ambiguous, or "floating" in electrical engineering parlance.
This site is awesome. That was my first post, and I certainly didn't expect responses!
Please let me share my perspective. A typical person has no idea how a digital circuit does the things it does, but a curious and intelligent person, when presented with the opportunity, would be eager to find out.
I believe an essential feature of a logic gate is that it is cascadable--the output of the logic gate is able to serve as an input to another logic gate. When a reader discovers this, and when he sees how switches/transistors can perform logic operations such as AND, his computer is no longer magical--it is merely complex. If a logic gate is treated as a device that obstructs or allows the flow of electricity from point A to point B, the idea of cascadability is lost, or at least postponed.
I understand the difficulties of treating this accurately. Many readers will not be familiar with concepts like voltage, current, and resistance. But I do think that an ideal writeup must convey the idea of cascadability somehow. I think I will concede that the logic gate currently in the writeup is pedagogically acceptable even without a pulldown resistor--technicalities could be covered in writeups on digital logic schemes (e.g. CMOS). My fundamental complaints are that the inputs and outputs are undefined and that it is unclear how the output will be used at the next logic stage.
I have added the following to try to clear up the issue:
Yeah, this article has been for 5+ years failing to make the distinction between the ideal model and physical devices. The distinction is now made in the lead, but it still lacking a section on that. Presumably, the effort here was to describe just ideal logic gates that can implemented in many ways (not necessarily electronic), but there no article on electronic logic gate (and the term is not really used), so this article should describe that stuff as well. Any textbook on microelectronics will do. Tijfo098 ( talk) 18:50, 7 April 2011 (UTC)
Where is the tri-state article ? This is clearly not the right article to talk about tri-state tristate 3-state logic gates (such as the 74356, the 74HC125, etc.). Is " transmission gates" really the best place ? Where in the encyclopedia is the right place ?
Am I seeing things or are the 'alternate AND' and 'alternate OR' labels switched on the diagram? For example: De Morgan's law says that P AND Q = NOT ((NOT P) OR (NOT Q)), i.e. there is an OR gate in the 'alternate AND' gate and vice versa. Also, following the circuits visually, it looks like they are switched. Varuna 22:22, 2005 Mar 10 (UTC)
I know that from several citations I've seen, that it is known that an "AND" gate will produce more heat than a "NOT" gate, because under quantum theory, information is destroyed and is released as heat (information is a very weird property in quantum theory), whereas an "NOT" gate merely converts information. Would it be good to try to elaborate some of this issue here? -- Natalinasmpf 03:35, 19 Apr 2005 (UTC)
Somewhere, probably not on a Web page, there's got to be some real history of the logic gate. The Tesla and Stowger patents referred to in previous versions of this article do not claim anything I can see called a "logic gate" or a functional equal. A mechanical logical-AND function must go back at least as far as the first lock with a key in it. I don't think you can patent the idea of logic alone, but I'd be happier if someone cited a patent that had as a major claim the idea that logical functions can be performed automatically. It may not be patentable at all. Babbage's difference engine predates even Tesla. -- Wtshymanski 22:05, 19 May 2005 (UTC)
Right - Ive had a good hack at the article and have made the first section especially more readable. I have lined up all the switch digrams with the relevant truth table and have also put these next to the relevant paragraph, and put each one in its own little section (i know it makes the ToC longer, but hey) I've also uploaded a modified version ofthe Alternate AND/OR diagram to show the NAND/NOR (I hope dypsrosia doesn't mind) gates. Also, I have done an article on making gates form NAND gates only, and uploaded shiny new blue jpgs of every gate and the NAND equivalent.
I've uploaded a new version of the little summary table thing (Truth2.jpg), and done pages for the XOR and XNOR gates (IC Pinouts and stuff), rather than for the logical process. These are now under XOR_gate and XNOR_gate. the XOR and XNOR articles both have updated headers giving directions.
This article also needs directions to those pages, perhaps when the other pages to do with the actual gates are done...
Also can someone do new versions of the rectangular symbols the present ones look a bit old and tatty...something like the 'military' symbols on this page. Also someonee might want to think about changin any links to the blue symbols to the military black and white ones if they would be better that way (so, for example NOT the ones in the diagrams on the NAND_logic page, but the symbol at the top of the XOR page maybe).
-- Jjbeard 05:35, 25 December 2005 (UTC)
The rectangular symbols have now been changed - the old ones still exist, but these are neater and easier to read.
Jjbeard 14:33, 25 December 2005 (UTC)
Your table markup could be simplified a lot.
INPUT | OUTPUT | |
---|---|---|
A | B | A AND B |
0 | 0 | 0 |
1 | 0 | 0 |
0 | 1 | 0 |
1 | 1 | 1 |
INPUT | OUTPUT | |
---|---|---|
A | B | A AND B |
0 | 0 | 0 |
1 | 0 | 0 |
0 | 1 | 0 |
1 | 1 | 1 |
Maybe not as pretty, though. Just a thought... — Omegatron 22:08, 23 January 2006 (UTC)
"They are primarily implemented electronically but can also be constructed using electromagnetic relays, electronic diodes, fluidics, optical or even mechanical elements."
In this part I will delete "electronic diodes" because they are included formerly in "implemented electronically". User:Vanished user 8ij3r8jwefi 15:41, 6 February 2006 (UTC)
This article has a couple of problems that I hope to address here before editing the page if appropriate: -Firstly, and most importantly, there is no real definition of a logic gate. Specifically it should be defined that it performs a logic operation on 1 or more inputs to create a single output. There is need to define the logic levels here. Then explain how inputs can be outputs of other gates. The switch analogy used here is completely misleading. It tends to suggest, especially for the NAND circuits, that 3 inputs are required, that is the two switches pressed and the electrical signal itself. It is important that nothing to do with electricity is used at all in defining logic gates, which are a logical concept. Having swithes arranged so that a circuit becomes closed when A and B switches are pressed does not make a logical gate. -Background does not say why diode logic cannt be used for all gates. Nor are any examples given of how to make gates different ways (there are only misleading switch circuits). -The tri state section implies tristate is merely to help designers. This is totally incorrect. Tristate greatly reduces the amount of circuity involved when many components (video cards, memory etc. connect to the same bus). Anyway i'll be doing some edits soon so like to know what you all think.
occasionally i've come accross symbols with the bubbles on the inputs (e.g. a NAND gate would be drawn as an or symbol with a bublle on each input). The idea being that you keep the core symbols for thier logical function and use the bublles to indicate a lines active state (then if you have a bubble feeding a non-bubble or vice-versa you have located a potential design error).
Anyone else encountered theese and do you think we should mention them? Plugwash 23:28, 12 February 2006 (UTC)
Am I the only one who refers to XNOR as XAND? Harvestdancer 19:37, 3 April 2006 (UTC)
I was looking at this page, and I am rather new to transistors and boolean logic (about a few months to a year or so), and I was wondering how a NOT gate can be made using transistors, much like the AND gates (below) are shown how to be made using transistors. From what I know, it's not possible, as is shown in the misleading pictures of the NOT gate on the Logic Gates page for example (the picture to the left), for transistors to be constantly on and SHUT-OFF with an electrical current applied to the gate (the "P" in NPN), or is it possible for a current applied to the GATE of a transistor (the A in the picture of the NOT gate to the left) to SHUT-OFF the current passing through the transistor? -- TAz69x 23:57, 16 April 2006 (UTC)
For example, the way transistors work (from what I know) is that NO CURRENT can flow through the N to N in NPN without the gate or the "P" in NPN having a current applied to it. So, like the picture to the left, when a current is applied to the gate(s), the connection is established, flowing from the left through both transistors to the OUT. [From what I know] both NPN and PNP gates work like this. But I don't think there is a way to STOP a current from flowing through the transistor by applying a current to the gate, or is there (like the about NOT gate transistor examples shows)? By this, I mean that for a NOT gate, to turn a 1 into a 0, (ONE into a ZERO), you'd have to somehow allow a gate to be DISABLED by applying a current to it, wouldn't you? And you would also have to allow a 0 to turn into a 1 as well; to have the current be ENABLED with no current or something (the boolean NOT gate would have to have one of its inputs register NO CURRENT, a binary 0 (ZERO), then would have to somehow let a current flow through the emitter to the collector to allow it to follow through the circuit to register as a 1 (eg. a NOT gate changing a ZERO (no current) into a ONE (current). So anyways, how would you produce a NOT gate with transistors? -- TAz69x 23:57, 16 April 2006 (UTC)
For example, a relay (like a transistor but with an electromagnet + a moving switch) could be set up with a spring so that when an electrical current is applied to the electromagnet (the "gate"), it breaks the current of the switch, effectively making a NOT gate with a relay. For example, a constant current would be applied to the switch, and when a current hits the relay, a 1, the switch would be broken, with the result being a 0. But when a zero (no current) is applied to the relay, the switch would remain, giving a result of 1, effectively creating a NOT gate!
But transistors don't work like that. A transistor can't be SHUT-OFF WITH a CURRENT, can they? Is there a difference between NPN transistpors and PNP transistors? Can PNP transistors be SHUT-OFF with a current applied to the gate?, as opposed to NPN transistors where a current applied to the gate TURNS-ON the transistor current from emitter to collector.
Anyways, my real question was just how can a NOT gate be formed with transistors, diodes, and/or resistors. Any combination of the three things to create a NOT gate would be GREATLY appreciated, and most importantly, a DIAGRAM!!! Thanks. -- TAz69x 23:57, 16 April 2006 (UTC)
VCC | |R2| | +------Y |C B+-+-+ A--|R1|--|T1 | <- NPN transistor +-+-+ |E GND
Aside from my above question, I was hoping that these questions could be answered as well if possible:
- Are there any definitive sites or articles here or anywhere else that show cascading as was mentioned above? What cascading is, how it works, how it can be implemented in an integrated circuits, etc. Preferably sites/articles that allow amateurs and professionals alike to understand the material?
- Are there any sites/articles that show more in-depth boolean logic circuit designs (eg. addition, subtraction, multiplication, etc.). Graphically what they may look like, tips for designing, etc.
- Are there any programs for windows that allow you to play around with boolean logic designs and create some integrated circuit designs graphically?
- Are there any sites/articles that explain how integrated circuits work with the electricity passing through them? Eg. How is it that for an arithmetic unit for example, how an integrated circuit keeps from some transistors/boolean-gates from having the electricity moving through them faster than other parts. For example, you have a 4-bit binary adder, and the numbers on the right begin passing through the adders and answer parts before other parts of the adder are able to come up with an answer. Are there ways that integrated circuits are designed that they can "wait" for an answer, by waiting until ALL FOUR out-ports of the integrated circuit adder have an answer ready? And if so, how could this be implementer, that an integrated circuit could be designed so that parts of it can wait until all necessary parts which are to give an answer for example have all finished up before passing the answer to a new part of the integrated circuit for example? Perhaps capacitors are used to temorarily store the answers of individual components of the chip until they are all full and can be passed on to the next part of the integrated circuit? And if so, how could this be implemented in the integrated circuit with transistors for example so that this would work? Maybe an article/site that explains this (preferably to amateurs as well!).
- Are there any sites/articles that show how to create boolean logic-gates with transistors, diodes, and/or resistors? I was wondering how these gates can be implemented using physics objects instead of just conceptually on paper.
Please feel free to answer ANY ONE of these questions at any time, but please answer the first NOT GATE first if possible! But if not and you have an answer to any of the other ones, then please don't hesitate to answer one of the other ones! Thanks for your help!
I would recommend reading the logic family article. Your asking a very broad question because there are many different flavors of logic which differ on the physical components used. Adam Y ( talk) 14:52, 19 May 2008 (UTC)
what is a INHIBIT logic gate? V8rik 22:34, 20 April 2006 (UTC)
I would like to publicize the article CMOS#Example: NAND gate which gives a clear physical layout of a NAND gate (The A and B inputs are implied; you would have to add metal layers to pads surrounding this gate). By the repeated application of the Sheffer stroke operator (NAND), it is possible to build up combinations of NANDs to yield the other logic gates, of course. -- Ancheta Wis 09:16, 28 April 2006 (UTC)
Does anyone have any references to the historical development of the electronic circuit symbols and language? When did it start, who started using drawings to do a combination of logic and electronics? etc. These would be good issues address in the article. Sholto Maud 10:58, 6 June 2006 (UTC)
Excelent article, very usefull. Thanks to all editors. -- 201.6.161.117 04:56, 10 September 2006 (UTC)
I think it would be really nifty if this article on logic gates had (or linked to) a drawing/schematic for each known implementation of logic gates. We have ladder logic and some of the many kinds of transistor-based logic gates. I want to add hydraulic "spool valve" logic gates and neon lamp logic gates.
The neon lamp article mentions "In the 1960s General Electric (GE), Signalite, and other firms made ... neon lamps for electronic uses. They even devised digital logic circuits, binary memories, and frequency dividers using neons."
I understand how to make logic gates out of transistors. How is it possible to make logic gates out of neon bulbs?
With a bit of googling, I've found a schematic for a 3 bulb sequential flasher/oscillator [6], and photographs of a neon bulb ring counter [7].
Could some help me reverse-engineer a schematic for that ring counter, or help me puzzle out some other logic circuit (NOT, NAND, NOR) using neons? (Using neons, diodes, resistors, and capacitors -- but no integrated circuits or discrete transistors or relays).
Is this something that needs to go into the logic gate article or the neon lamp article? -- 70.189.77.59 13:07, 28 October 2006 (UTC)
NOR_gate has it's own article, while NAND_gate points back to this article. Is there a NAND_gate article coming, or is the NOR_gate article going to be merged into this one? I would rather see a separate NAND article myself. Ken6en 08:10, 30 October 2006 (UTC) Oops, I see the problem... NAND_Gate points to this article, and NAND_gate is an existing article. I'll change all references to NAND_Gate back to NAND_gate. Ken6en 08:14, 30 October 2006 (UTC)
Are the values of Not A and Not B transposed?
Should it not be added to the intro paragraph that logic gates can be formed out of several neurons? —Preceding unsigned comment added by 140.247.44.93 ( talk) 19:34, 6 November 2007 (UTC)
Is there any chip commercially available with a million logic gates? I am not sure if the number of logic gates match the number of transistors. [9] Anwar ( talk) 17:24, 10 May 2008 (UTC)
Yes, several field-programmable gate array chips and other chips contain well over a million logic gates. Each logic gate is built out of some integer number of transistors. Most integrated circuits manufactured recently are built using CMOS, using 2 transistors for a NOT gate, 6 transistors for a 3-in NAND gate, etc. Counting transistors is a more objective method of measuring the size of an integrated circuit than counting logic gates, because many integrated circuits include a bunch of transistors outside of any recognizable logic gate, such as in register file and DRAM. -- 68.0.124.33 ( talk) 19:31, 2 October 2008 (UTC)
Is there a connection between what is known as 'relay logic' and the topics covered here? It seems that people are using on this page what looks similar to the diagrams used in relay logic. So, is relay logic some kind of basic ingredient to depicting logic gates? Peeceepeh ( talk) 14:42, 30 June 2008 (UTC)
74CBT3253 dual 4way transmission gate MUX with a pair of XOR like 74LVC2G86 makes a great ALU slice. 5 ohms and 250pS through, so cascades like a relay and may propagate several slices without ripple before needing a buffer. Or build same of qty3 DPDT relays with free XOR across coils. What makes transmission gates relevant to relays is the option to solve a prefixed chain of switches by series current. Only the critical path of propagation really cares if switched-through or driven-combinatorial. See also Manchester Carry, ignoring anything about precharged dominoes... Ken KD5ZXG 20230609
Why is the output of a logic gate usually named Q? -- Abdull ( talk) 20:37, 28 August 2008 (UTC)
If I understand "A Tinkertoy computer" by A. K. Dewdney correctly, a set of things is is "computation universal" if, given sufficient quantities of those things, you can build a Turing complete machine out of it.
When this article mentions that "diode logic... is an incomplete form of logic. ... To build a complete logic system, valves (vacuum tubes) or transistors can be used.", by "complete" I think it means the same kind of "computation universal".
The "functional completeness" article seems to be about highly abstract "logical connectives" in formal logic -- is there some other article that focuses more on the various concrete devices that are "computation universal"?
However, the functional completeness article is the closest thing Wikipedia has to this concept of "computation universal" that I know about, so -- until I find a better article -- I'm going to link that phrase in this article to the "functional completeness" article. -- 68.0.124.33 ( talk) 04:45, 14 September 2008 (UTC)
I deleted the claim that "clocks [are] signals that oscillate with a known period", because not all clock signals oscillate with a known period. For example, spread spectrum#Spread-spectrum clock signal generation. -- 68.0.124.33 ( talk) 21:51, 13 January 2009 (UTC)
I've made a new table for the logic functions. I put it in a template here, as it seems to me that this could be useful for other pages.
INPUT | A | 0 | 0 | 1 | 1 | Meaning | |
---|---|---|---|---|---|---|---|
B | 0 | 1 | 0 | 1 | |||
OUTPUT | FALSE | 0 | 0 | 0 | 0 | Whatever A and B, output is false. Contradiction. | |
A AND B | 0 | 0 | 0 | 1 | Output is true if and only if (iff) both A and B are true. | ||
A B | 0 | 0 | 1 | 0 | A doesn't imply B. True if A but not B. | ||
A | 0 | 0 | 1 | 1 | True whenever A is true. | ||
A B | 0 | 1 | 0 | 0 | A is not implied by B. True if not A but B. | ||
B | 0 | 1 | 0 | 1 | True whenever B is true. | ||
A XOR B | 0 | 1 | 1 | 0 | True if A is not equal to B. | ||
A OR B | 0 | 1 | 1 | 1 | True if A is true, or B is true, or both. | ||
A NOR B | 1 | 0 | 0 | 0 | True if neither A nor B. | ||
A XNOR B | 1 | 0 | 0 | 1 | True if A is equal to B. | ||
NOT B | 1 | 0 | 1 | 0 | True if B is false. | ||
A B | 1 | 0 | 1 | 1 | A is implied by B. False if not A but B, otherwise true. | ||
NOT A | 1 | 1 | 0 | 0 | True if A is false. | ||
A B | 1 | 1 | 0 | 1 | A implies B. False if A but not B, otherwise true. | ||
A NAND B | 1 | 1 | 1 | 0 | A and B are not both true. | ||
TRUE | 1 | 1 | 1 | 1 | Whatever A and B, output is true. Tautology. |
I've put in links to the more obscure functions (implication, non-implication, etc). It seems to me that the current explanatory text under the table is a bit confused, especially as the material implication is what is usually meant by AB, rather than logical implication (=entailment). While the two are very closely related, the material implication is the logical connective that links values in a truth table. Inductiveload ( talk) 02:32, 28 January 2009 (UTC)
What is discrete logic? This term currently redirect to logic gate, but it is not explained what it means. Thanks, -- Abdull ( talk) 23:31, 8 February 2010 (UTC)
I have made some minor edits correcting the "Symbols" section. As the chairman of IEEE SCC11.9 and U.S. delegate to IEC TC3 WG2 over the many years the respective standards were written and revised, I am quite certain of the accuracy, so please forgive my presumptuousness in editing directly. Feel free to contact me if you have any questions.
-Tom Smith
smith@alum.mit.edu —Preceding unsigned comment added by 71.232.120.146 ( talk) 21:13, 8 June 2010 (UTC)
This article is very unclear. I opened it wondering what a logic gate is, and closed it with no greater understanding than I came with. It explains logic gates in great detail to those who already have an idea of what they are, but offer no insight to those who don't. —Preceding unsigned comment added by 90.36.15.143 ( talk) 08:59, 16 August 2010 (UTC)
The article does not reveal the fundamental idea behind logic gates at all; it does not show how logical functions are implemented by various electronic circuits. Background (as it is written) is more suitable as an introductory part of Logic family. Circuit dreamer ( talk, contribs, email) 19:35, 7 April 2011 (UTC)
These changes look like vandalism:
http://en.wikipedia.org/?title=Logic_gate&action=historysubmit&diff=448953348&oldid=448552259
Perhaps someone more experienced could check and if needed undo them?
88.115.123.211 (
talk) 18:20, 7 September 2011 (UTC)
Can we create unit cell using logic gates which when stacked with itself can behave like Universal Turing Machine with head being single signal moving between cells? I am trying to implement Wolfram (2,3) UTM, but it works wrong — Preceding unsigned comment added by 83.21.106.70 ( talk) 18:49, 8 March 2012 (UTC)
There are a bunch of places such as in the symbols section where it says something along "In practice, these gates are built from combinations of simpler logic gates." (talking about XOR). This is a very misleading statement. "In practice" there are so many things that get considered that how it's actually implemented various wildly as to make that statement obsolete. Many times standard cell for XOR which would be used around (XOR2, XOR3, XOR4, etg..) as well depending on the requirements. There are simply way too many way these things are made to fit in one sentence "In practice, ...". -- CyberXRef ☎ 02:13, 24 March 2014 (UTC)
In the same vein, anon 76... describes a De Morgan equivalent applied to a motor. 76, I would appreciate a diagram to illustrate your latest contribution. -- Ancheta Wis (talk | contribs) 01:05, 26 March 2014 (UTC)
There have been some attempts to document obsolete DIN 40700 symbols in this article (retired in 1998). Although there may some who are fond of them, there are also some who are fond of a number of other obsolete standards. I think this article should confine itself to currently approved and active standards and not to the history of the evolution of those standards, which is extensive. Perhaps another article could take on that task.
I have consequently removed some inserted (and erroneous) material relating to the obsolete DIN standard, but added clarification regarding the current standard and retained a reference to another article for those who might be interested in the history of the last 40 years. — Preceding unsigned comment added by 66.30.92.163 ( talk) 15:32, 21 April 2015 (UTC)
Since the page Discrete_circuit seems unnecessary, I think it's best to remove the "redirects here, for x see y". Discrete_circuit should redirect to Electronic_circuit instead, what do you think? See also: /info/en/?search=Talk:Discrete_circuit#Removal_of_page-- Tielemans.jorim ( talk) 17:01, 31 May 2015 (UTC)
The text here (starting at "In electronics, a NOT gate is more commonly called an inverter") appears to be taken from the text under the NOT gate in the table on this page. The copyright date of the book is 2014, and the text was on the Wikipedia page as of 2013, so it seems unlikely that Wikipedia is the guilty party. The book doesn't seem to provide a citation, nor be under an acceptable license - furrykef ( Talk at me) 15:06, 18 March 2016 (UTC)
The symbols shown in the main article for exclusive-OR are defined in IEC 60617-12 and IEEE Std 91 as an exclusive-OR function only for two inputs (IEEE symbol 5.1-11, IEC symbol 12-27-09). There is no defined distinctive-shape symbol with more than two inputs for any function other than AND, OR, and their inverts.
For rectangular-shape symbols, there are a series of related symbols that have defined meanings with multiple inputs. The IEEE symbols listed below can be found as IEC symbols 12-27-01 through -09.
"=m" - IEEE symbol 5.1-6, m and only m function, of which "=1" (5.1-11) is a special case. The output is true iff exactly m inputs are true.
">=m" - IEEE symbol 5.1-5, threshold function, of which ">=1" (5.1-1) is a special case. The output is true iff at least m inputs are true.
">n/2" - IEEE symbol 5.1-7, majority function. The output is true iff more than half the inputs are true.
"=" - IEEE symbol 5.1-8, identity function. The output is true iff all inputs are in the same state.
"2k+1" - IEEE symbol 5.1-9, odd function. The output is true iff the number of true inputs is odd.
"2k" - IEEE symbol 5.1-10, even function. The output is true iff the number of true inputs is even. — Preceding unsigned comment added by 73.47.87.95 ( talk) 16:52, 2 July 2016 (UTC)
I tried to add one of the OR boolean algebra symbols as listed on the List of logic symbols page, but it was reverted as lacking a reference. Currently AND gate lists , as notations but not . OR lists but not or . Should these alternative boolean algebra notations be listed? What if any ref is required? Izyt ( talk) 18:51, 28 October 2016 (UTC)
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Please see the paragraph beginning ' 3. The concepts "positive-true logic" and "negative-true logic" ' in my section "Less esoteric usage and better explanation required" in talk:Open collector. Hedles ( talk) 15:35, 12 February 2020 (UTC)
I think this topic is duplicated in the article. I think that the Electronic gates subsection should also be split into physical manufacturing and overview of logic families. AXONOV (talk) ⚑ 15:46, 24 December 2021 (UTC)
Hi there folks! Just wanted to open this thread to discuss a small change I made to the table in the Universal logic gates section of the article.
The XOR gate built from NOR gates in the table is the one which, according to the XOR gate article, "offers the advantage of a shorter propagation delay":
Whereas the XNOR gate built from NAND gates in the table was originally the one which, according to the XNOR gate article, actually has more propagation delay:
I figured it would probably be more appropriate - from both the perspective of (a) the table consistently showing the version of the gate with less propagation delay, and (b) symmetry and duality between XNOR/XOR ↔ NAND/NOR - to instead have the table show this version of the XNOR gate built from NAND gates:
I imagine this was just a minor oversight, probably due to the filename of the last image being XNOR from NAND 2.svg
, while none of the rest of the filenames have that 2
in them. However, I'm not an electronics expert by any means! So please feel free to revert my edit, if in fact there was some other underlying reason for this asymmetry of which I'm just not aware.
Indnwkybrd ( talk) 02:38, 23 October 2023 (UTC)
Perhaps the most noteworthy implication of Tesla’s radio-controlled automaton, however, was demonstration of the basic “AND-gate” function that would become an indispensable element of all subsequent electronic and computer logic. His inspiration for this concept reportedly came from studying the work of Victorian biologist and philosopher Herbert Spencer regarding the combined action of two or more nerves in the human body. Tesla’s original implementation employed two sets of transmitters and receivers operating on different radio frequencies to trigger a pair of detector relays. Both these relays had to close at the same time in order to energize a third, which in turn incremented a mechanical escapement driving a rotary switch to decode the command. Tesla’s dual-receiver design provided a relay-based AND-gate function that allowed the contacts of R3 to close only when both R1 and R2 were activated by their respective signals (digitally enhanced from US Patent No. 725,605, awarded 14 April 1903). I feel like Tesla should at least be mentioned as having made an AND gate first. I realize it was not a modern gate, however it did function just like a modern gate. 162.246.112.154 ( talk) 17:27, 21 April 2024 (UTC)
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Skoch3 ( talk) 19:55, 7 January 2010 (UTC)Anthony, Larry, AND I changed the language explaining that all the gates can be constructed from either NAND or NOR gates. We wrote: "All other types of Boolean logic gates (i.e., AND, OR, NOT, XOR, XNOR) can be created from a suitable network of NAND gates. Similarly all gates can be created from a network of NOR gates. Historically, NAND gates were easier to construct from MOS technology and thus NAND gates served as the first pillar of Boolean logic in electronic computation."
NAND and NOR gates in NMOS or CMOS both look equally complex/simple. Are you sure you don't mean TTL, where the multi-emitter input allows NAND gates to be much simpler than NOR gates? 60.241.12.136 ( talk) 11:43, 8 July 2010 (UTC)
The images are for the American standard for gate symbols. The European, which I belive is the real standard (approved by ISO/ANSI or something), standard looks different. An AND gate is a square with an ampersand in it, OR is a square with >= 1 in it and so on. I couldn't find any pics for them though. :-( asdfasdfsdf
The article mentions Nikola Tesla having patented logic gates as US645576, but I looked up that patent, "System of transmission of electrical energy", and it appears to describe a means of transmitting electricity through the air, but nothing to do with logic gates. I've taken the reference to that patent out of the article. -- Arteitle 19:51, Mar 7, 2004 (UTC)
The relevant patents are US 723,188 and US 725,605 granted in 1903. They were filed as one application in July 1900 but subsequently divided. I have added them to the text. Conception of the idea was at least as far back as 1896, '...I have an instinctive knowledge of the same...' Tesla said during the interference deposition for the patent, (US Patent Office Interference No 21,701, Systems of Signaling, Nikola Tesla vs. Reginald A. Fessenden, 1902, reply to question 9, August 5th 1902)-- Smark33021 21:32, 23 Dec 2004 (UTC)
I'm new here, so I don't want to make any changes. I shall note, however, that logic gates used in digital integrated circuitry do not operate in this manner. The author is conveying the idea that a logic gate either allows a signal to pass (in his diagram from left to right) or doesn't allow a signal to pass. While this seems sensible to the novice, it is not correct.
The reason that the author's conception of logic gate cannot be used in digital circuitry is that when a signal is not allowed to pass--for instance, if one transistor in his AND gate is OFF--the signal (technically the voltage level) on the OUT end of his logic gate is ambiguous, or "floating" in electrical engineering parlance.
This site is awesome. That was my first post, and I certainly didn't expect responses!
Please let me share my perspective. A typical person has no idea how a digital circuit does the things it does, but a curious and intelligent person, when presented with the opportunity, would be eager to find out.
I believe an essential feature of a logic gate is that it is cascadable--the output of the logic gate is able to serve as an input to another logic gate. When a reader discovers this, and when he sees how switches/transistors can perform logic operations such as AND, his computer is no longer magical--it is merely complex. If a logic gate is treated as a device that obstructs or allows the flow of electricity from point A to point B, the idea of cascadability is lost, or at least postponed.
I understand the difficulties of treating this accurately. Many readers will not be familiar with concepts like voltage, current, and resistance. But I do think that an ideal writeup must convey the idea of cascadability somehow. I think I will concede that the logic gate currently in the writeup is pedagogically acceptable even without a pulldown resistor--technicalities could be covered in writeups on digital logic schemes (e.g. CMOS). My fundamental complaints are that the inputs and outputs are undefined and that it is unclear how the output will be used at the next logic stage.
I have added the following to try to clear up the issue:
Yeah, this article has been for 5+ years failing to make the distinction between the ideal model and physical devices. The distinction is now made in the lead, but it still lacking a section on that. Presumably, the effort here was to describe just ideal logic gates that can implemented in many ways (not necessarily electronic), but there no article on electronic logic gate (and the term is not really used), so this article should describe that stuff as well. Any textbook on microelectronics will do. Tijfo098 ( talk) 18:50, 7 April 2011 (UTC)
Where is the tri-state article ? This is clearly not the right article to talk about tri-state tristate 3-state logic gates (such as the 74356, the 74HC125, etc.). Is " transmission gates" really the best place ? Where in the encyclopedia is the right place ?
Am I seeing things or are the 'alternate AND' and 'alternate OR' labels switched on the diagram? For example: De Morgan's law says that P AND Q = NOT ((NOT P) OR (NOT Q)), i.e. there is an OR gate in the 'alternate AND' gate and vice versa. Also, following the circuits visually, it looks like they are switched. Varuna 22:22, 2005 Mar 10 (UTC)
I know that from several citations I've seen, that it is known that an "AND" gate will produce more heat than a "NOT" gate, because under quantum theory, information is destroyed and is released as heat (information is a very weird property in quantum theory), whereas an "NOT" gate merely converts information. Would it be good to try to elaborate some of this issue here? -- Natalinasmpf 03:35, 19 Apr 2005 (UTC)
Somewhere, probably not on a Web page, there's got to be some real history of the logic gate. The Tesla and Stowger patents referred to in previous versions of this article do not claim anything I can see called a "logic gate" or a functional equal. A mechanical logical-AND function must go back at least as far as the first lock with a key in it. I don't think you can patent the idea of logic alone, but I'd be happier if someone cited a patent that had as a major claim the idea that logical functions can be performed automatically. It may not be patentable at all. Babbage's difference engine predates even Tesla. -- Wtshymanski 22:05, 19 May 2005 (UTC)
Right - Ive had a good hack at the article and have made the first section especially more readable. I have lined up all the switch digrams with the relevant truth table and have also put these next to the relevant paragraph, and put each one in its own little section (i know it makes the ToC longer, but hey) I've also uploaded a modified version ofthe Alternate AND/OR diagram to show the NAND/NOR (I hope dypsrosia doesn't mind) gates. Also, I have done an article on making gates form NAND gates only, and uploaded shiny new blue jpgs of every gate and the NAND equivalent.
I've uploaded a new version of the little summary table thing (Truth2.jpg), and done pages for the XOR and XNOR gates (IC Pinouts and stuff), rather than for the logical process. These are now under XOR_gate and XNOR_gate. the XOR and XNOR articles both have updated headers giving directions.
This article also needs directions to those pages, perhaps when the other pages to do with the actual gates are done...
Also can someone do new versions of the rectangular symbols the present ones look a bit old and tatty...something like the 'military' symbols on this page. Also someonee might want to think about changin any links to the blue symbols to the military black and white ones if they would be better that way (so, for example NOT the ones in the diagrams on the NAND_logic page, but the symbol at the top of the XOR page maybe).
-- Jjbeard 05:35, 25 December 2005 (UTC)
The rectangular symbols have now been changed - the old ones still exist, but these are neater and easier to read.
Jjbeard 14:33, 25 December 2005 (UTC)
Your table markup could be simplified a lot.
INPUT | OUTPUT | |
---|---|---|
A | B | A AND B |
0 | 0 | 0 |
1 | 0 | 0 |
0 | 1 | 0 |
1 | 1 | 1 |
INPUT | OUTPUT | |
---|---|---|
A | B | A AND B |
0 | 0 | 0 |
1 | 0 | 0 |
0 | 1 | 0 |
1 | 1 | 1 |
Maybe not as pretty, though. Just a thought... — Omegatron 22:08, 23 January 2006 (UTC)
"They are primarily implemented electronically but can also be constructed using electromagnetic relays, electronic diodes, fluidics, optical or even mechanical elements."
In this part I will delete "electronic diodes" because they are included formerly in "implemented electronically". User:Vanished user 8ij3r8jwefi 15:41, 6 February 2006 (UTC)
This article has a couple of problems that I hope to address here before editing the page if appropriate: -Firstly, and most importantly, there is no real definition of a logic gate. Specifically it should be defined that it performs a logic operation on 1 or more inputs to create a single output. There is need to define the logic levels here. Then explain how inputs can be outputs of other gates. The switch analogy used here is completely misleading. It tends to suggest, especially for the NAND circuits, that 3 inputs are required, that is the two switches pressed and the electrical signal itself. It is important that nothing to do with electricity is used at all in defining logic gates, which are a logical concept. Having swithes arranged so that a circuit becomes closed when A and B switches are pressed does not make a logical gate. -Background does not say why diode logic cannt be used for all gates. Nor are any examples given of how to make gates different ways (there are only misleading switch circuits). -The tri state section implies tristate is merely to help designers. This is totally incorrect. Tristate greatly reduces the amount of circuity involved when many components (video cards, memory etc. connect to the same bus). Anyway i'll be doing some edits soon so like to know what you all think.
occasionally i've come accross symbols with the bubbles on the inputs (e.g. a NAND gate would be drawn as an or symbol with a bublle on each input). The idea being that you keep the core symbols for thier logical function and use the bublles to indicate a lines active state (then if you have a bubble feeding a non-bubble or vice-versa you have located a potential design error).
Anyone else encountered theese and do you think we should mention them? Plugwash 23:28, 12 February 2006 (UTC)
Am I the only one who refers to XNOR as XAND? Harvestdancer 19:37, 3 April 2006 (UTC)
I was looking at this page, and I am rather new to transistors and boolean logic (about a few months to a year or so), and I was wondering how a NOT gate can be made using transistors, much like the AND gates (below) are shown how to be made using transistors. From what I know, it's not possible, as is shown in the misleading pictures of the NOT gate on the Logic Gates page for example (the picture to the left), for transistors to be constantly on and SHUT-OFF with an electrical current applied to the gate (the "P" in NPN), or is it possible for a current applied to the GATE of a transistor (the A in the picture of the NOT gate to the left) to SHUT-OFF the current passing through the transistor? -- TAz69x 23:57, 16 April 2006 (UTC)
For example, the way transistors work (from what I know) is that NO CURRENT can flow through the N to N in NPN without the gate or the "P" in NPN having a current applied to it. So, like the picture to the left, when a current is applied to the gate(s), the connection is established, flowing from the left through both transistors to the OUT. [From what I know] both NPN and PNP gates work like this. But I don't think there is a way to STOP a current from flowing through the transistor by applying a current to the gate, or is there (like the about NOT gate transistor examples shows)? By this, I mean that for a NOT gate, to turn a 1 into a 0, (ONE into a ZERO), you'd have to somehow allow a gate to be DISABLED by applying a current to it, wouldn't you? And you would also have to allow a 0 to turn into a 1 as well; to have the current be ENABLED with no current or something (the boolean NOT gate would have to have one of its inputs register NO CURRENT, a binary 0 (ZERO), then would have to somehow let a current flow through the emitter to the collector to allow it to follow through the circuit to register as a 1 (eg. a NOT gate changing a ZERO (no current) into a ONE (current). So anyways, how would you produce a NOT gate with transistors? -- TAz69x 23:57, 16 April 2006 (UTC)
For example, a relay (like a transistor but with an electromagnet + a moving switch) could be set up with a spring so that when an electrical current is applied to the electromagnet (the "gate"), it breaks the current of the switch, effectively making a NOT gate with a relay. For example, a constant current would be applied to the switch, and when a current hits the relay, a 1, the switch would be broken, with the result being a 0. But when a zero (no current) is applied to the relay, the switch would remain, giving a result of 1, effectively creating a NOT gate!
But transistors don't work like that. A transistor can't be SHUT-OFF WITH a CURRENT, can they? Is there a difference between NPN transistpors and PNP transistors? Can PNP transistors be SHUT-OFF with a current applied to the gate?, as opposed to NPN transistors where a current applied to the gate TURNS-ON the transistor current from emitter to collector.
Anyways, my real question was just how can a NOT gate be formed with transistors, diodes, and/or resistors. Any combination of the three things to create a NOT gate would be GREATLY appreciated, and most importantly, a DIAGRAM!!! Thanks. -- TAz69x 23:57, 16 April 2006 (UTC)
VCC | |R2| | +------Y |C B+-+-+ A--|R1|--|T1 | <- NPN transistor +-+-+ |E GND
Aside from my above question, I was hoping that these questions could be answered as well if possible:
- Are there any definitive sites or articles here or anywhere else that show cascading as was mentioned above? What cascading is, how it works, how it can be implemented in an integrated circuits, etc. Preferably sites/articles that allow amateurs and professionals alike to understand the material?
- Are there any sites/articles that show more in-depth boolean logic circuit designs (eg. addition, subtraction, multiplication, etc.). Graphically what they may look like, tips for designing, etc.
- Are there any programs for windows that allow you to play around with boolean logic designs and create some integrated circuit designs graphically?
- Are there any sites/articles that explain how integrated circuits work with the electricity passing through them? Eg. How is it that for an arithmetic unit for example, how an integrated circuit keeps from some transistors/boolean-gates from having the electricity moving through them faster than other parts. For example, you have a 4-bit binary adder, and the numbers on the right begin passing through the adders and answer parts before other parts of the adder are able to come up with an answer. Are there ways that integrated circuits are designed that they can "wait" for an answer, by waiting until ALL FOUR out-ports of the integrated circuit adder have an answer ready? And if so, how could this be implementer, that an integrated circuit could be designed so that parts of it can wait until all necessary parts which are to give an answer for example have all finished up before passing the answer to a new part of the integrated circuit for example? Perhaps capacitors are used to temorarily store the answers of individual components of the chip until they are all full and can be passed on to the next part of the integrated circuit? And if so, how could this be implemented in the integrated circuit with transistors for example so that this would work? Maybe an article/site that explains this (preferably to amateurs as well!).
- Are there any sites/articles that show how to create boolean logic-gates with transistors, diodes, and/or resistors? I was wondering how these gates can be implemented using physics objects instead of just conceptually on paper.
Please feel free to answer ANY ONE of these questions at any time, but please answer the first NOT GATE first if possible! But if not and you have an answer to any of the other ones, then please don't hesitate to answer one of the other ones! Thanks for your help!
I would recommend reading the logic family article. Your asking a very broad question because there are many different flavors of logic which differ on the physical components used. Adam Y ( talk) 14:52, 19 May 2008 (UTC)
what is a INHIBIT logic gate? V8rik 22:34, 20 April 2006 (UTC)
I would like to publicize the article CMOS#Example: NAND gate which gives a clear physical layout of a NAND gate (The A and B inputs are implied; you would have to add metal layers to pads surrounding this gate). By the repeated application of the Sheffer stroke operator (NAND), it is possible to build up combinations of NANDs to yield the other logic gates, of course. -- Ancheta Wis 09:16, 28 April 2006 (UTC)
Does anyone have any references to the historical development of the electronic circuit symbols and language? When did it start, who started using drawings to do a combination of logic and electronics? etc. These would be good issues address in the article. Sholto Maud 10:58, 6 June 2006 (UTC)
Excelent article, very usefull. Thanks to all editors. -- 201.6.161.117 04:56, 10 September 2006 (UTC)
I think it would be really nifty if this article on logic gates had (or linked to) a drawing/schematic for each known implementation of logic gates. We have ladder logic and some of the many kinds of transistor-based logic gates. I want to add hydraulic "spool valve" logic gates and neon lamp logic gates.
The neon lamp article mentions "In the 1960s General Electric (GE), Signalite, and other firms made ... neon lamps for electronic uses. They even devised digital logic circuits, binary memories, and frequency dividers using neons."
I understand how to make logic gates out of transistors. How is it possible to make logic gates out of neon bulbs?
With a bit of googling, I've found a schematic for a 3 bulb sequential flasher/oscillator [6], and photographs of a neon bulb ring counter [7].
Could some help me reverse-engineer a schematic for that ring counter, or help me puzzle out some other logic circuit (NOT, NAND, NOR) using neons? (Using neons, diodes, resistors, and capacitors -- but no integrated circuits or discrete transistors or relays).
Is this something that needs to go into the logic gate article or the neon lamp article? -- 70.189.77.59 13:07, 28 October 2006 (UTC)
NOR_gate has it's own article, while NAND_gate points back to this article. Is there a NAND_gate article coming, or is the NOR_gate article going to be merged into this one? I would rather see a separate NAND article myself. Ken6en 08:10, 30 October 2006 (UTC) Oops, I see the problem... NAND_Gate points to this article, and NAND_gate is an existing article. I'll change all references to NAND_Gate back to NAND_gate. Ken6en 08:14, 30 October 2006 (UTC)
Are the values of Not A and Not B transposed?
Should it not be added to the intro paragraph that logic gates can be formed out of several neurons? —Preceding unsigned comment added by 140.247.44.93 ( talk) 19:34, 6 November 2007 (UTC)
Is there any chip commercially available with a million logic gates? I am not sure if the number of logic gates match the number of transistors. [9] Anwar ( talk) 17:24, 10 May 2008 (UTC)
Yes, several field-programmable gate array chips and other chips contain well over a million logic gates. Each logic gate is built out of some integer number of transistors. Most integrated circuits manufactured recently are built using CMOS, using 2 transistors for a NOT gate, 6 transistors for a 3-in NAND gate, etc. Counting transistors is a more objective method of measuring the size of an integrated circuit than counting logic gates, because many integrated circuits include a bunch of transistors outside of any recognizable logic gate, such as in register file and DRAM. -- 68.0.124.33 ( talk) 19:31, 2 October 2008 (UTC)
Is there a connection between what is known as 'relay logic' and the topics covered here? It seems that people are using on this page what looks similar to the diagrams used in relay logic. So, is relay logic some kind of basic ingredient to depicting logic gates? Peeceepeh ( talk) 14:42, 30 June 2008 (UTC)
74CBT3253 dual 4way transmission gate MUX with a pair of XOR like 74LVC2G86 makes a great ALU slice. 5 ohms and 250pS through, so cascades like a relay and may propagate several slices without ripple before needing a buffer. Or build same of qty3 DPDT relays with free XOR across coils. What makes transmission gates relevant to relays is the option to solve a prefixed chain of switches by series current. Only the critical path of propagation really cares if switched-through or driven-combinatorial. See also Manchester Carry, ignoring anything about precharged dominoes... Ken KD5ZXG 20230609
Why is the output of a logic gate usually named Q? -- Abdull ( talk) 20:37, 28 August 2008 (UTC)
If I understand "A Tinkertoy computer" by A. K. Dewdney correctly, a set of things is is "computation universal" if, given sufficient quantities of those things, you can build a Turing complete machine out of it.
When this article mentions that "diode logic... is an incomplete form of logic. ... To build a complete logic system, valves (vacuum tubes) or transistors can be used.", by "complete" I think it means the same kind of "computation universal".
The "functional completeness" article seems to be about highly abstract "logical connectives" in formal logic -- is there some other article that focuses more on the various concrete devices that are "computation universal"?
However, the functional completeness article is the closest thing Wikipedia has to this concept of "computation universal" that I know about, so -- until I find a better article -- I'm going to link that phrase in this article to the "functional completeness" article. -- 68.0.124.33 ( talk) 04:45, 14 September 2008 (UTC)
I deleted the claim that "clocks [are] signals that oscillate with a known period", because not all clock signals oscillate with a known period. For example, spread spectrum#Spread-spectrum clock signal generation. -- 68.0.124.33 ( talk) 21:51, 13 January 2009 (UTC)
I've made a new table for the logic functions. I put it in a template here, as it seems to me that this could be useful for other pages.
INPUT | A | 0 | 0 | 1 | 1 | Meaning | |
---|---|---|---|---|---|---|---|
B | 0 | 1 | 0 | 1 | |||
OUTPUT | FALSE | 0 | 0 | 0 | 0 | Whatever A and B, output is false. Contradiction. | |
A AND B | 0 | 0 | 0 | 1 | Output is true if and only if (iff) both A and B are true. | ||
A B | 0 | 0 | 1 | 0 | A doesn't imply B. True if A but not B. | ||
A | 0 | 0 | 1 | 1 | True whenever A is true. | ||
A B | 0 | 1 | 0 | 0 | A is not implied by B. True if not A but B. | ||
B | 0 | 1 | 0 | 1 | True whenever B is true. | ||
A XOR B | 0 | 1 | 1 | 0 | True if A is not equal to B. | ||
A OR B | 0 | 1 | 1 | 1 | True if A is true, or B is true, or both. | ||
A NOR B | 1 | 0 | 0 | 0 | True if neither A nor B. | ||
A XNOR B | 1 | 0 | 0 | 1 | True if A is equal to B. | ||
NOT B | 1 | 0 | 1 | 0 | True if B is false. | ||
A B | 1 | 0 | 1 | 1 | A is implied by B. False if not A but B, otherwise true. | ||
NOT A | 1 | 1 | 0 | 0 | True if A is false. | ||
A B | 1 | 1 | 0 | 1 | A implies B. False if A but not B, otherwise true. | ||
A NAND B | 1 | 1 | 1 | 0 | A and B are not both true. | ||
TRUE | 1 | 1 | 1 | 1 | Whatever A and B, output is true. Tautology. |
I've put in links to the more obscure functions (implication, non-implication, etc). It seems to me that the current explanatory text under the table is a bit confused, especially as the material implication is what is usually meant by AB, rather than logical implication (=entailment). While the two are very closely related, the material implication is the logical connective that links values in a truth table. Inductiveload ( talk) 02:32, 28 January 2009 (UTC)
What is discrete logic? This term currently redirect to logic gate, but it is not explained what it means. Thanks, -- Abdull ( talk) 23:31, 8 February 2010 (UTC)
I have made some minor edits correcting the "Symbols" section. As the chairman of IEEE SCC11.9 and U.S. delegate to IEC TC3 WG2 over the many years the respective standards were written and revised, I am quite certain of the accuracy, so please forgive my presumptuousness in editing directly. Feel free to contact me if you have any questions.
-Tom Smith
smith@alum.mit.edu —Preceding unsigned comment added by 71.232.120.146 ( talk) 21:13, 8 June 2010 (UTC)
This article is very unclear. I opened it wondering what a logic gate is, and closed it with no greater understanding than I came with. It explains logic gates in great detail to those who already have an idea of what they are, but offer no insight to those who don't. —Preceding unsigned comment added by 90.36.15.143 ( talk) 08:59, 16 August 2010 (UTC)
The article does not reveal the fundamental idea behind logic gates at all; it does not show how logical functions are implemented by various electronic circuits. Background (as it is written) is more suitable as an introductory part of Logic family. Circuit dreamer ( talk, contribs, email) 19:35, 7 April 2011 (UTC)
These changes look like vandalism:
http://en.wikipedia.org/?title=Logic_gate&action=historysubmit&diff=448953348&oldid=448552259
Perhaps someone more experienced could check and if needed undo them?
88.115.123.211 (
talk) 18:20, 7 September 2011 (UTC)
Can we create unit cell using logic gates which when stacked with itself can behave like Universal Turing Machine with head being single signal moving between cells? I am trying to implement Wolfram (2,3) UTM, but it works wrong — Preceding unsigned comment added by 83.21.106.70 ( talk) 18:49, 8 March 2012 (UTC)
There are a bunch of places such as in the symbols section where it says something along "In practice, these gates are built from combinations of simpler logic gates." (talking about XOR). This is a very misleading statement. "In practice" there are so many things that get considered that how it's actually implemented various wildly as to make that statement obsolete. Many times standard cell for XOR which would be used around (XOR2, XOR3, XOR4, etg..) as well depending on the requirements. There are simply way too many way these things are made to fit in one sentence "In practice, ...". -- CyberXRef ☎ 02:13, 24 March 2014 (UTC)
In the same vein, anon 76... describes a De Morgan equivalent applied to a motor. 76, I would appreciate a diagram to illustrate your latest contribution. -- Ancheta Wis (talk | contribs) 01:05, 26 March 2014 (UTC)
There have been some attempts to document obsolete DIN 40700 symbols in this article (retired in 1998). Although there may some who are fond of them, there are also some who are fond of a number of other obsolete standards. I think this article should confine itself to currently approved and active standards and not to the history of the evolution of those standards, which is extensive. Perhaps another article could take on that task.
I have consequently removed some inserted (and erroneous) material relating to the obsolete DIN standard, but added clarification regarding the current standard and retained a reference to another article for those who might be interested in the history of the last 40 years. — Preceding unsigned comment added by 66.30.92.163 ( talk) 15:32, 21 April 2015 (UTC)
Since the page Discrete_circuit seems unnecessary, I think it's best to remove the "redirects here, for x see y". Discrete_circuit should redirect to Electronic_circuit instead, what do you think? See also: /info/en/?search=Talk:Discrete_circuit#Removal_of_page-- Tielemans.jorim ( talk) 17:01, 31 May 2015 (UTC)
The text here (starting at "In electronics, a NOT gate is more commonly called an inverter") appears to be taken from the text under the NOT gate in the table on this page. The copyright date of the book is 2014, and the text was on the Wikipedia page as of 2013, so it seems unlikely that Wikipedia is the guilty party. The book doesn't seem to provide a citation, nor be under an acceptable license - furrykef ( Talk at me) 15:06, 18 March 2016 (UTC)
The symbols shown in the main article for exclusive-OR are defined in IEC 60617-12 and IEEE Std 91 as an exclusive-OR function only for two inputs (IEEE symbol 5.1-11, IEC symbol 12-27-09). There is no defined distinctive-shape symbol with more than two inputs for any function other than AND, OR, and their inverts.
For rectangular-shape symbols, there are a series of related symbols that have defined meanings with multiple inputs. The IEEE symbols listed below can be found as IEC symbols 12-27-01 through -09.
"=m" - IEEE symbol 5.1-6, m and only m function, of which "=1" (5.1-11) is a special case. The output is true iff exactly m inputs are true.
">=m" - IEEE symbol 5.1-5, threshold function, of which ">=1" (5.1-1) is a special case. The output is true iff at least m inputs are true.
">n/2" - IEEE symbol 5.1-7, majority function. The output is true iff more than half the inputs are true.
"=" - IEEE symbol 5.1-8, identity function. The output is true iff all inputs are in the same state.
"2k+1" - IEEE symbol 5.1-9, odd function. The output is true iff the number of true inputs is odd.
"2k" - IEEE symbol 5.1-10, even function. The output is true iff the number of true inputs is even. — Preceding unsigned comment added by 73.47.87.95 ( talk) 16:52, 2 July 2016 (UTC)
I tried to add one of the OR boolean algebra symbols as listed on the List of logic symbols page, but it was reverted as lacking a reference. Currently AND gate lists , as notations but not . OR lists but not or . Should these alternative boolean algebra notations be listed? What if any ref is required? Izyt ( talk) 18:51, 28 October 2016 (UTC)
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Please see the paragraph beginning ' 3. The concepts "positive-true logic" and "negative-true logic" ' in my section "Less esoteric usage and better explanation required" in talk:Open collector. Hedles ( talk) 15:35, 12 February 2020 (UTC)
I think this topic is duplicated in the article. I think that the Electronic gates subsection should also be split into physical manufacturing and overview of logic families. AXONOV (talk) ⚑ 15:46, 24 December 2021 (UTC)
Hi there folks! Just wanted to open this thread to discuss a small change I made to the table in the Universal logic gates section of the article.
The XOR gate built from NOR gates in the table is the one which, according to the XOR gate article, "offers the advantage of a shorter propagation delay":
Whereas the XNOR gate built from NAND gates in the table was originally the one which, according to the XNOR gate article, actually has more propagation delay:
I figured it would probably be more appropriate - from both the perspective of (a) the table consistently showing the version of the gate with less propagation delay, and (b) symmetry and duality between XNOR/XOR ↔ NAND/NOR - to instead have the table show this version of the XNOR gate built from NAND gates:
I imagine this was just a minor oversight, probably due to the filename of the last image being XNOR from NAND 2.svg
, while none of the rest of the filenames have that 2
in them. However, I'm not an electronics expert by any means! So please feel free to revert my edit, if in fact there was some other underlying reason for this asymmetry of which I'm just not aware.
Indnwkybrd ( talk) 02:38, 23 October 2023 (UTC)
Perhaps the most noteworthy implication of Tesla’s radio-controlled automaton, however, was demonstration of the basic “AND-gate” function that would become an indispensable element of all subsequent electronic and computer logic. His inspiration for this concept reportedly came from studying the work of Victorian biologist and philosopher Herbert Spencer regarding the combined action of two or more nerves in the human body. Tesla’s original implementation employed two sets of transmitters and receivers operating on different radio frequencies to trigger a pair of detector relays. Both these relays had to close at the same time in order to energize a third, which in turn incremented a mechanical escapement driving a rotary switch to decode the command. Tesla’s dual-receiver design provided a relay-based AND-gate function that allowed the contacts of R3 to close only when both R1 and R2 were activated by their respective signals (digitally enhanced from US Patent No. 725,605, awarded 14 April 1903). I feel like Tesla should at least be mentioned as having made an AND gate first. I realize it was not a modern gate, however it did function just like a modern gate. 162.246.112.154 ( talk) 17:27, 21 April 2024 (UTC)