lets say I have one switch assume it's a buffer, if the input is ON then the output is ON , if the input is OFF then the output is OFF !
assume that I was having input "ON" then the output is "ON" ! , now I got new "ON" from other circuits that's connected to my buffer,
what I'm thinking now like that : Now I'm having new "ON", so it will go to the buffer, but the buffer have already previous "ON", so I get:
previous "ON"=new "ON" ; as a result now the previous "ON" will be deleted because of coming new "ON" and the new "ON" will be entered the buffer.... here is MY PROBLEM ! how does the previous "ON" get deleted?! maybe my analogous isn't correct?! if it's not correct, then how should I think about it?! any suitable analogous?

thanks beforehand

 

[Where did the previous '1' go?]
It didn't go anywhere. It's the same '1' after the changed input as before the change.

 

What is baffled me, I'm assuming that the pins "inputs" and "outputs" are saving something like saving data (0/1) and that's the problem maybe they are not saving data and just like something memoryless !

 

Meaning with smashed, if there's a previous data, the new coming data will smash the previous data, meaning the previous data will be deleted!

I'm not understanding if there's a previous data according to concrete inputs and afterwards I changed the inputs which leads to change the output, so the output now changed !, where the previous data "GONE"?! that's what really confusing me !

You seem to be thinking that the output is somehow stored someplace and that it must first be deleted before new data can be stored in its place. That's not how a logic gate works.

Imagine a lamp that has two switches in parallel such that either switch being ON turns the lamp on while it requires both switches being OFF for the lamp to turn off. So now imagine that one switch is ON and the other is OFF. Now you walk in and flick the second switch to ON. What happens to the prior output? Nothing. The lamp stays on without interruption. It just went from having one switch driving it to now both switches are driving it.

 

What is baffled me, I'm assuming that the pins "inputs" and "outputs" are saving something like saving data (0/1) and that's the problem maybe they are not saving data and just like something memoryless !

You keep saying you know how the gate works. It's clear that you don't. Like I said before, a gate doesn't store a value someplace and then delete it and store a new value. Logic gates, particularly CMOS logic gates, are nothing but a bunch of switches (transistors) that are either open or closed based on the input signals.

 

Hi doesn't matter what the circuit is

It *always* matters what the circuit is.

ak

 

Human beings can be really stubborn when it comes to preconceived notions. Combinatorial logic , consisting of gates with NO memory, provide continuous outputs. The idealization is that the outputs are '1' or '0'. Look at an output with an oscilloscope and you will see the continuous nature of the output. In the '1' state there is noise and movement in what looks like a totally random walk with a range of a few tens of miilivolts around and average level of say 3.3 VDC. In the '0' state there is noise and movement in what looks like a totally random walk with a range of a few tens of millivolts around and average level of 0 VDC, aka GROUND. You can also see the transitions fro '1' to '0' and '0' to '1' which take place over a period of several tens of nanoseconds. They look a great deal like linear ramps. The important point is they are continuous in a quite rigorous mathematical sense. There are other things to see, but there is never ever a discontinuity in the output of a combinatorial gate.

 

It *always* matters what the circuit is.

ak

Pay attention to what AK says. What he is saying is that all circuits are analog. Digital circuits are merely a convenient abstraction.

 

[Where did the previous '1' go?]
It didn't go anywhere. It's the same '1' after the changed input as before the change.

see my last comments, but wasn't there previous '1'?! shouldn't I differentiate between new '1' and previous '1' ? what I'm actually imagining that the output like saving data and the new coming data(0/1) will smash the previous data(delete the previous) , and if it's actually what happened then previous data "gone" , where is it gone?!

once again I'm not trolling or something, that's problem facing me about two weeks !

 

Read post #24 and #25 carefully few more times, and try to understand what the poster said.

That answer is actually answering all your doubts.

Allen

 

Human beings can be really stubborn when it comes to preconceived notions. Combinatorial logic , consisting of gates with NO memory, provide continuous outputs. The idealization is that the outputs are '1' or '0'. Look at an output with an oscilloscope and you will see the continuous nature of the output. In the '1' state there is noise and movement in what looks like a totally random walk with a range of a few tens of miilivolts around and average level of say 3.3 VDC. In the '0' state there is noise and movement in what looks like a totally random walk with a range of a few tens of millivolts around and average level of 0 VDC, aka GROUND. You can also see the transitions fro '1' to '0' and '0' to '1' which take place over a period of several tens of nanoseconds. They look a great deal like linear ramps. The important point is they are continuous in a quite rigorous mathematical sense. There are other things to see, but there is never ever a discontinuity in the output of a combinatorial gate.

THANKS VERY MUCH !
to be frankly with you I was imagining that it's memoryless but wasn't known actually there's in life a components that are memoryless !!

 

Pay attention to what AK says. What he is saying is that all circuits are analog. Digital circuits are merely a convenient abstraction.

I understand you, what do you mean with "convenient abstraction" , meaning something that we are tolerated with in our roleplay life?

 

o the output now changed !, where the previous data "GONE"

In a sense, yes.
But logically it's exactly the same and the following circuits cannot tell any difference.
It's sort of a Zen question.

 

Pay attention to what AK says. What he is saying is that all circuits are analog. Digital circuits are merely a convenient abstraction.

That, and the fact that there are at least a half dozen fundamentally different circuits that would present the behavior described in post #1.

ak

 

In a sense, yes.
But logically it's exactly the same and the following circuits cannot tell any difference.
It's sort of a Zen question.

So we are always just going according our intuition in the whole field of studying ! am I right ? that all students act like that !

 

In a sense, yes.
But logically it's exactly the same and the following circuits cannot tell any difference.
It's sort of a Zen question.

Something akin to the sound of one hand clapping. I like it!

 

I understand you, what do you mean with "convenient abstraction" , meaning something that we are tolerated with in our roleplay life?

No, nothing of the sort. The convenient abstraction allows us to analyze and synthesize a close to ideal digital circuit with analog components. Once we understand the limitations we can use the abstraction to create devices of much greater complexity than we could by remaining in the analog domain.

 

You keep saying you know how the gate works. It's clear that you don't. Like I said before, a gate doesn't store a value someplace and then delete it and store a new value. Logic gates, particularly CMOS logic gates, are nothing but a bunch of switches (transistors) that are either open or closed based on the input signals.

thank you !
if I was having switch which was "ON" , then it means that the switch is passing "current", I got new "1" from other circuits that connected to my switch, now will it switch from ON to ON because I got new "1"? or just after getting new "1" it keeps the switch ON without any change between previous "1" and new "1"?
I believe that the PC can switch from 0 to 1 and from 1 to 0, what about if I was in 0 and got new 0 then the switch is switching from 0 to 0?! or if I was having 1, and got new "1" then the switch is switching from 1 to 1? but it doesn't make sense to swtich from state to the same previous state ...

Moreover to clear more, exactly determining which if the state is ON or OFF is dramatically dependent only just on the inputs's state ! meaning if the switch was ON and I changed the inputs which the new output is "1" then it means ON, but actually I was having ON from the previous state(assumed that) so after changing ... the state of previous switch will continue as ON after changing to new state and PC will not touch it for switching from ON to ON because it's already ON... am I right? guess so

 

thank you !
if I was having switch which was "ON" , then it means that the switch is passing "current", I got new "1" from other circuits that connected to my switch, now will it switch from ON to ON because I got new "1"? or just after getting new "1" it keeps the switch ON without any change between previous "1" and new "1"?
I believe that the PC can switch from 0 to 1 and from 1 to 0, what about if I was in 0 and got new 0 then the switch is switching from 0 to 0?! or if I was having 1, and got new "1" then the switch is switching from 1 to 1? but it doesn't make sense to swtich from state to the same previous state ...

Moreover to clear more, exactly determining which if the state is ON or OFF is dramatically dependent only just on the inputs's state ! meaning if the switch was ON and I changed the inputs which the new output is "1" then it means ON, but actually I was having ON from the previous state(assumed that) so after changing ... the state of previous switch will continue as ON after changing to new state and PC will not touch it for switching from ON to ON because it's already ON... am I right? guess so

Don't think of it as "switching" from a 1 to a 1. Think of it as "staying" a 1. The only thing that is changing is "why" it is a 1.

 

Don't think of it as "switching" from a 1 to a 1. Think of it as "staying" a 1. The only thing that is changing is "why" it is a 1.

I understand you very much ! so it's not like it will down from 1 to 0 for "nano seconds" and then up to 1 ....because we would get "OFF" for nano seconds and that's not logically

thanks !