The state machine sequencer

A project log for The Cardboard Computer - IO is my name

My goal is a 4-bit CPU using recycled cardboard substrate and Diode Transistor Logic. This is an educational platform for me.

Dr. CockroachDr. Cockroach 12/22/2016 at 09:484 Comments

I needed to start looking into the FSM part of this project and found a circuit that outputs 5 pulses for every 2 clock pulses ( I cant remember who posted this but if your out there reading then please chime in ). This should help head off any problems with propagation delays along the chain of command. A J-K toggle flip-flop is used to input to the sequencer. ( by the way, I do now have Logisim and Qucs as simulators on my notebook so I can check out the circuits ahead of time. The J-K on the left using nor gates and sequencer on the right using nand gates.

I had a senior moment - The link for the FSM sequencer circuit is Rory Mangles and his TinyTim at


Nicky Nickell wrote 12/23/2016 at 04:10 point

You should take a look at logisim-evolution ( as well.

Additionally, Falstad's circuit simulator ( might also be useful if you want to tinker on a circuit at the component level instead of logic gates.

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Yann Guidon / YGDES wrote 12/22/2016 at 20:20 point


I can't "read" the wires, could you show a schematic view ?

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Dr. Cockroach wrote 12/22/2016 at 22:18 point

Hi there, I added the Logisim layout. Only diff is I used a J-k for real

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Yann Guidon / YGDES wrote 12/22/2016 at 22:19 point

thanks ! this "speaks" to me better :-)

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