Talk:Combinational logic

message: :The following discussion is an archived debate of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section. 
The result of the debate was move. —Nightstallion (?) Seen this already? 11:49, 8 May 2006 (UTC)
thread_title: Untitled

message: There has been a lot of debate about the use of the two terms, esp see wiki discussion of FPGAs.  It is my observation that the language usage appears to have drifted.  It would be interesting to nail this down to the specifics.  But what I can offer is the following concrete observation.  Back in the 1970's, when I first learned Boolean Algebra, the text book (title not recalled) on the subject very definitely taught Combinatorial Logic and I never encountered the term Combinational.  Recently I decided to learn how to program an FPGA.  The text book I purchased "Digital Design with Digilent FPGA boards", starts off with a review of Boolean Algebra and talks about Combinational Logic.   In the wiki FPGA discussion there is also further anecdotal evidence that other old-timers like me learned Combinatorial Logic, but the newer generation of people are learning Combinational Logic -- it's the same thing only the name has changed.  Therefore I conclude that somewhere in the past 35 years, without any fanfare, the language usage has drifted.  Before I started studying contemporary text books/FPGAs, Back in the mid 80's I switched my focus from electronics to software, I had never encountered the term Combinational Logic in my work as a computer programmer, but now that I am getting back into electronics design, the term Combinational seems to be the majority usage.  Conclusion, both terms are valid, but Combinatorial is the older term and Combinational is the newer term that is now in popular use.  When or why this shift occurred is a topic for further research.  codeslinger compsalot (not motivated to create an account) 06:11, 18 November 2011 (UTC)
replies: text: I guess I'm one of the oldtimers that was taught "combinatorial", like several others mentioned at talk: field-programmable gate array#"Combinational" vs. "Combinatorial". I agree with codeslinger: This article should briefly mention the transition. I'd like to know the reason that certain companies switched from one term to another. Was it just random chance, new documents written by newly hired people from a different linguistic region? Or has anyone at these companies hinted that they deliberately changed their house style, and for what reason? --DavidCary (talk) 13:32, 9 November 2012 (UTC)
replies: text:  The "Terminology" section here was very short, and a bit vague ("some people", etc.), so I merged it with the lead and explicitly stated that the terminology was controversial. The term "combinatorial" is very common, at least in my engineering community, and though I personally consider it less correct, I think it needs to be mentioned in the lead, as readers may be confused at having to dig into the article to find it . --Fru1tbat (talk) 14:12, 12 March 2014 (UTC)
thread_title:  Combinatorial versus Combinational an Historic Perspective 

message: * The important concept that should be explained in Wikipedia is the difference between combinatorial circuits and sequential circuits.  Combinatorial circuits are just boolean functions and can be described using boolean logic. Sequential circuits are combinatorial circuits plus memories; they can be described as state machines, and their external properties can be described using temporal logic (see Bochmann 1982, E.M. Clarke and Bud Mishra 1983, and many others since). In seqiential circuits, the outputs depend on the inputs and past history, while in combinatorial circuits, the outputs only depend on the inputs.
* The fact that "sequential circuit" redirects to "sequential logic" is a nonsense, it should just be the opposite. It is just because hardware designers use the term logics in their dialect. There is no mathematical concept of "sequential logic", because such logic is just the same as Boolean logic. And this is very obvious in this page: all the algebraic laws given are just plain ordinary Boolean laws. 
* To stress the previous point, I don't think that there is a distinct mathematical field such as "combinational logic". This is just Boolean logic. In this respect, having a Wikipedia page "Combinational logic" at the same level as other relevant pages such as "Temporal logic" for instance (which is a relevant concept) is questionable. So, my message would be: ok for a "combinational circuit" article, but not for "combinational logic".
* The emphasis on truth tables and Boolean simplifications is obsolete: in practice, these methods do not scale to non-toy examples. The relevant methods used for designing circuits are BDD (Binary Decision Diagrams), SAT solvers, etc.
* The debate "combinational vs combinatorial" is not essential. Just to mention that the argument "combinational wins by 4:1 on Google" is no longer valid. As of Nov. 2011, I see on Google 474,000 results for "combinational logic" and 291,000 results for "combinatorial logic". And it may be the case that Wikipedia's choice influences Google, who knows.  — Preceding unsigned comment added by Vasywriter (talk • contribs) 17:13, 19 November 2011 (UTC)
thread_title:  This page is really disappointing/confusing and should be deeply reorganized 

message: I just noticed that this article is listed under the "Philosophy articles" category.  That is a totally inappropriate classification.  Although is can be said that George Bool was himself a Philosopher; the actual use and implementation of Boolean Algebra is purely to do with the design of electronic circuits and computers software/hardware.  More appropriate categories would be Computer Science, Electronics, Computer Programming, and Mathematics.  codeslinger 08:17, 21 November 2011 (UTC)
thread_title:  this article is miscatergorized 

message: The equations used in the article are fine -- as far as they go -- but notation is weird.  While it is true that a lot of different symbolic notations are used, I would strongly suggest that this article use the more conventional/familiar symbols/notation such as those used by Verilog or VHDL.  codeslinger 08:30, 21 November 2011 (UTC)
thread_title:  equations are fine but notation is weird 

message: If I am right, combinational logic should allow many-valued logic, as long as it is a finite-valued logic (e.g. three-valued logic), but obviously not Infinite-valued logic (real-valued logic).— TentaclesTalk or ✉ mailto:Tentacles 18:45, 24 July 2018 (UTC)
thread_title:  Combinational logic with many-valued logic 

message: Might be worth mentioning that the output of any practical combinatorial logic circuit does not instantaneously change when one of its inputs change. It takes time for the change to ripple through the circuit. 75.149.30.179 (talk) 15:34, 11 December 2019 (UTC)
thread_title:  Time independence, Practice vs. Theory