What are logic gates

Question

Hi,

Are logic gates only considered physical? if they are a physical object, what are they exactly? are they only the model? a clear and easy explanation of what logic gates actually entail would be very helpful. I'm having difficulty understanding them based on the articles I've found. I'm looking for further my understanding of how computers work.

Thank you for your help.

Answer 1

Mich ,

this something you can find in the web easily. i have just used google for it and the first hit was this:

https://en.m.wikipedia.org/wiki/Logic_gate

Answer 2

thanks to Calvin Thomas and Mich for asking questions and Martin Taylor for answering it .. really learned a lot ....
😂i too had a myth that it all runs through some nanoscale BJTs. after watching nand to tetris .
@Martin Taylor are you electrical engineer?! you have a good knowledge about all these stuffs .. if not then from where you learn all these stuffs?! (probably some random articles and experiences i guess...)

Willing to share this with ChillPill sir too ...

Answer 3

Think of a logic gate as an on and off switch... When voltage passes through, it's on and when potential difference is 0 then it's off.

Logic gates are mainly used in Boolean problems which are like on/off, 1/0 or True/ False statements.

Let's say you are writing a program and it's work is to count numbers in a loop so each time an number is added e.g +1 , the gate will take that as on, 1 or True and it will let the current pass through...

I think you should read more from here :

https://www.tutorialspoint.com/computer_logical_organization/logic_gates.htm

Answer 4

I mean, is logic physical? It doesn't seem to be, but in order to convey logic, something in the physical world has to move from one location to another. My understanding is that the term "logic gates" refer to the model, and its common physical implementation in computers involves transistors.

http://hyperphysics.phy-astr.gsu.edu/hbase/Electronic/trangate.html

Of course, that hasn't stopped creative minds from attempting to build fully mechanical computing units:

like via marbles
https://youtu.be/8BOvLL8ok8I

or even water...
https://youtu.be/IxXaizglscw

Answer 5

Martin Taylor is an electrical engineer. he said 4 months ago in Q/A:
"
My speciality is embedded real time systems and aerospace equipment. I'm retired in all but name these days. I started out on computers with 8K bytes of ferrite core memory. The processing power in a mobile phone was the stuff of science fiction when I started out.

I still remember Bill Gates commenting on the 1 MB limitation of MS-DOS that "1MB should be enough for anyone.". Yeah, that didn't age well Bill.
"
i always enjoy his answers

Answer 6

Kiwwi#
in old days terminal devices were just printers (yeah typewriter like) ..there werent any display like monitor it came later ... on every command you will have to wait for it to print the result ...
really the history of computers is incredibly amazing and there was art in everything ... Martin and Mehran were too lucky i can say that they are spectators of the era..

Answer 7

Martin Taylor I see, so I guess that there are some expensive possibilities to cancel out this capacitive reactance. Thank you very much for answering my questions.

Answer 8

Martin Taylor thats really fascinating
..
amazed to see that they had shift , control and alt keys too...

Answer 9

thank you

Answer 10

I have only ever known the term "logic gates" to mean physical transistor circuits or digital microchip components. In software it is called Boolean logic, Boolean expressions or just logic.

Answer 11

Mich Logic gates are physical semiconductor devices, made using diodes and transistors and sometimes, resistors (this needs to be clarified). However, the representations aren't.

Edit: I don't know much about the logic technologies used nowadays. From what I've Googled, TTL is actually faster (the ECL configuration is even faster) than CMOS (possibly due to the fact that it doesn't pose that much of capacitive reactance at high frequencies) but it consumes more power, while the CMOS logic consumes lesser power as the only one contributing to the power intake is the capacitive transient at the start, which is pretty small for low frequencies. Also, MOSFETs can deliver more output power than BJTs. But they're not so suitable for high-speed applications because of its Gate-Source capacitance. Moreover, CMOS is more expensive than TTL logic.

Answer 12

Martin Taylor Oh, that's right. Thanks for the correction. Even when I was typing this, I just needed to think for a while whether the inefficient resistor-transistor logic is still used. It seems that they're really inefficient and outdated; maybe because it's easier for me to implement one, I had preferred to type this out. So, are modern gates manufactured using MOSFETS? Or is it something else?

Answer 13

its boolean logic, and (&&) or (||) not (!) operators are used to decide if a condition is true or false

Answer 14

Martin Taylor I see. What about FETs? Do they perform better than BJTs?

Answer 15

Logic gates are digital electronics related thing as like 01 concept
0 = 0000, 1= 0001, 2= 0010... extra. By the way this is deep machine learning thing min like 128bit 64bit 32bit 16bit 8bit 4bit 2bit 1bit
Logically binary count start from 1 bit example if 10 = 8bit + 2bit min 1010 one( turn on) zero( turn off)
If you I want to make a CPU or GPU like processing chips then you need to understand deeply logic gates works... it's also use full data structure logic thing program size and time complexity... it min these things DAIRECT related with hardware that's why...

Answer 16

thank you all so much for helping me out

Answer 17

Indeed logic gates are physical stuff, if you want to know how stuff works you should learn digital electronics, its an amazing subject to learn and you will love it.

Answer 18

Prashanth Kumar I don't belong to that era.It hasn't been long since I met the computer.

Answer 19

Logic gates are made of transistors and diodes ,therfore yes they are physical.THEY ARE ELECTRICAL COMPONENTS USED TO PERFORM BASIC LOGICAL FUNCTIONS AND IS CONSIDERED AS THE FUNDAMENTAL BUILDING BLOCKS OF S DIGITAL CIRCUIT.

Answer 20

I'll review, thank you