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Author Topic: Anyone use Logisim?  (Read 49532 times)

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Offline AngelFish

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Re: Anyone use Logisim?
« Reply #30 on: December 01, 2010, 09:02:50 pm »
Quote from: Xeda112358 on December 01, 2010, 09:01:15 pm
What is the logic called where if both bits are the same, the output bit is 1. Isn't XOR 1 if the inputs are different?

It's the AND operation, otherwise denoted by ∧.

Darn it, not evil anymore.
« Last Edit: December 01, 2010, 09:03:31 pm by Qwerty.55 »
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∂²Ψ    -(2m(V(x)-E)Ψ
---  = -------------
∂x²        ℏ²Ψ

Offline Xeda112358

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Re: Anyone use Logisim?
« Reply #31 on: December 01, 2010, 09:08:35 pm »
AND? AND only outputs a 1 if both bits are 1, doesn't it? What if it outputs 1 if both bits are 0, too?
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Offline AngelFish

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Re: Anyone use Logisim?
« Reply #32 on: December 01, 2010, 09:11:02 pm »
Oh, I thought you meant iff the bits were both 1. You'd probably have to do multiple gates chained together.
« Last Edit: December 01, 2010, 09:13:31 pm by Qwerty.55 »
Logged
∂²Ψ    -(2m(V(x)-E)Ψ
---  = -------------
∂x²        ℏ²Ψ

Offline Xeda112358

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Re: Anyone use Logisim?
« Reply #33 on: December 01, 2010, 09:12:46 pm »
Nevermind, I got it... XNOR

I made the circuit already, I just wanted to know what it was called :D
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Offline Builderboy

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Re: Anyone use Logisim?
« Reply #34 on: December 01, 2010, 09:54:53 pm »
Note to everybody using Logisim, it uses an advanced propagation routine that might trip a few people up.  For example try building this circuit.  have a regular clock, and attach it to an AND gate in two places.  Negate on of the wires with a NOT gate.  Take the output of the AND gate and attach it to an incremental register.  The register should never increase because the AND gate can never be satisfied right?

Wrong

For the brief milisecond that it takes for the clock pulse to travel through the NOT gate, the AND gate will be true for a tiny second and increment the counter.  This will not show in Logisim, as it only shows beginning and end states, and can lead to much confusion.  So remember, always make sure your logic is very solid and well build or else it might turn on you!
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Offline Xeda112358

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Re: Anyone use Logisim?
« Reply #35 on: December 01, 2010, 10:16:46 pm »
Okay, another logic problem...
(1,1)=0
(1,0)=1
(0,1)=0
(0,0)=0

If I use NOT on the second number, and then use AND, I get this result...
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Offline calc84maniac

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Re: Anyone use Logisim?
« Reply #36 on: December 01, 2010, 10:17:55 pm »
Quote from: Xeda112358 on December 01, 2010, 10:16:46 pm
Okay, another logic problem...
(1,1)=0
(1,0)=1
(0,1)=0
(0,0)=0

If I use NOT on the second number, and then use AND, I get this result...
How is that a problem? That looks perfectly correct to me...
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Offline Builderboy

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Re: Anyone use Logisim?
« Reply #37 on: December 01, 2010, 10:18:34 pm »
I think he's asking what the gate is?  Note that not all 16 combinations have names :)
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Offline Xeda112358

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Re: Anyone use Logisim?
« Reply #38 on: December 01, 2010, 10:19:39 pm »
Oh, okay. Thanks! I am having so much fun with this!
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Offline Runer112

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Re: Anyone use Logisim?
« Reply #39 on: December 01, 2010, 10:25:32 pm »
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Offline Xeda112358

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Re: Anyone use Logisim?
« Reply #40 on: December 01, 2010, 10:29:37 pm »
Thanks!

Converse non-implication?
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Offline AngelFish

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Re: Anyone use Logisim?
« Reply #41 on: December 01, 2010, 10:32:28 pm »
Actually that would be logical implication  ;)
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∂²Ψ    -(2m(V(x)-E)Ψ
---  = -------------
∂x²        ℏ²Ψ

Offline Xeda112358

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Re: Anyone use Logisim?
« Reply #42 on: December 01, 2010, 10:36:06 pm »
Hmm? It is only the value of p if q is not true, so it is "Material nonimplication" I think...
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Offline DJ Omnimaga

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Re: Anyone use Logisim?
« Reply #43 on: December 01, 2010, 11:32:03 pm »
By the way, I wonder if that software can be useful in helping the development of something like OTCalc or if it's just limited to motherboards, processors and the like?
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Offline Xeda112358

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Re: Anyone use Logisim?
« Reply #44 on: December 01, 2010, 11:37:47 pm »
Well, this is definitely giving us experience in designing the thing. We can make our own processors!
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