On 5/27/2010 5:48 AM, Invisible wrote:
> Invisible wrote:
>
>> http://www.play-hookey.com/digital/jk_nand_flip-flop.html
>>
>> This is significantly simpler than I had imagined! ;-)
>
> An RS flip-flop is not difficult to construct. I quickly discovered that
> if you connect to gated RS latches together, and connect both gate pins
> to the flip-flop's clock pin, but with one signal inverted, you get a
> clocked flip-flop. (Gratifyingly, I discovered the website above and
> found the exact same circuit design. So apparently I was right!)

Play-hookey is one of my favorites!

Yep, the J-K flip-flop works just like that.

> Converting a gated latch or a clocked flip-flop from RS-type to D-type
> is a trivial matter of adding an inverter. Making a toggle flip-flop

Actually, it gets better: You can make a D latch without adding the 
inverter (A latch isn't clocked. The same works with a flip-flop) by 
connecting one of the input gate's outputs to the other gate's input.

> just requires you to take a clocked D flip-flop and connect the inverted
> output back to the data input. The clock pin then becomes the toggle. So
> far so good.
>
> Now... how in the name of goodness do you add UNclocked set and reset
> pins?? o_O
>

Look at the "master" flip-flop. Keep in mind after the NAND gates that 
are controlled by the clock, that part is a S-R latch. By adding an 
extra input to those gates you can manually control the S and R signals. 
You'll notice after you connect inputs to these that you can now 
asynchronously control the output when the control is low.

Now, look downstream. when the clock is high, this no longer works, 
you'll need to defeat the clock on this part somehow. Also note when the 
clock is high, the signals from the nand gates on the first flip-flop 
will need to be suppressed.

Once you've figure this out... You'll need 4 new gates to get the S-R 
commands working.



-- 
~Mike

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Mike Raiford wrote:
> BTW:
> 
> http://sourceforge.net/projects/logicsim/
> 
> Requires .NET Framework 3.5
> 
> Only really just tiny pieces of the UI implemented, but you can sort of 
> see how it will work.

Hmm, interesting.

(I'm not sure what took longer - setting up a VM, installing .NET on it, 
defragging it afterwards, or trying to refind this post so I could 
reply! >_< )

So have you got any further with it yet? ;-)

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On 5/28/2010 6:41 AM, Invisible wrote:

> (I'm not sure what took longer - setting up a VM, installing .NET on it,
> defragging it afterwards, or trying to refind this post so I could
> reply! >_< )
>
> So have you got any further with it yet? ;-)

Yep.

I have the wiring completed now. I'm posting a new exe soon. I was kind 
of hoping to get your opinions of the UI as I move forward.

I'm trying to keep the app as flexible as possible without being 
unwieldy. The simulation core need some serious work, though.

I'm just hoping the people that download the app when it's complete 
won't roast me for using the .NET framework like they did on the other 
.NET app.

Also, probably due for a rename when it's more final judging by the 
similarity of the name of LogiSim. I created the project before I 
searched for other similar projects. That's how I found LogiSim in the 
first place. Shame on me. ;)

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>> So have you got any further with it yet? ;-)
> 
> Yep.
> 
> I have the wiring completed now. I'm posting a new exe soon. I was kind 
> of hoping to get your opinions of the UI as I move forward.

You probably want to start a new thread when you do... This subthread is 
fairly deeply burried. But sure, I'll look at it.

> I'm trying to keep the app as flexible as possible without being 
> unwieldy. The simulation core need some serious work, though.

I could point out several things I dislike about LogiSim that I hope you 
can avoid doing - but I think I'll just wait and see what you *have* 
done and comment on that. ;-)

> I'm just hoping the people that download the app when it's complete 
> won't roast me for using the .NET framework like they did on the other 
> .NET app.

I've got a VM with .NET on it now, so it should be fairly easy to test.

> Also, probably due for a rename when it's more final judging by the 
> similarity of the name of LogiSim. I created the project before I 
> searched for other similar projects. That's how I found LogiSim in the 
> first place. Shame on me. ;)

Well, let's see, you're writing a *logic* *simulator*. You might take a 
wild guess that similar existing products will have names consisting of 
some contraction of these two words... ;-)

It's like writing a Mandelbrot generator and calling it MandelPlot or 
something. I wouldn't be surprised at all if somebody has already taken 
that name.

Call it something random like POV-Wire or something. :-D

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