IO - The Inside Out Cardboard Computer - bis

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

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My goal is to build a four bit computer using recycled, re-purposed and just plain junk as the main construction material. Why? Well, the cardboard is free as my workplace puts it in the dumpster and I do not have the funds to buy better material. A very green build indeed. Except for the ALU, all logic cells are constructed on individual cardboard pads as basic Nand, Nor or other gates as basic building blocks.
This method of construction is open to anyone of any age who can solder and all circuits are wired point to point, no PC boards. A great hands on learning aid to see how digital logic works at the gate level. No black IC packages will be found at the end of this project.

The heart of this project is the Cardboard Logic Pad or CLP. With this construction method, any logic gate can be produced and pads can be combined for more complex logic circuits. This method started out by using thumb tacks pressed into wood panels. That method was not well suited to easy circuit modification and logic gates could not be inserted or removed easily. Using cardboard as a base material has proven to be easier to work with and is lighter in weight.

  • 1 × 2N3906 PNP Transistor
  • 2 × 1N4148 Diode
  • 1 × 3.9 K Resistor
  • 1 × 15 K Resistor
  • 1 × 22 K Resistor

View all 7 components

  • 1
    Step 1

    The Cardboard Logic Pad - The basic logic building block for the construction of IO

  • 2
    Step 2

    This is the start of building a Cardboard Logic Pad or CLP for short. The cardboard is found as scrap and the paper fasteners are from any local office supply or big box store. These fasteners take solder very well.

  • 3
    Step 3

    Select the gate circuit that is desired. In this case I am using my basic Nand gate circuit using a npn transistor and input diodes.

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Lee Djavaherian wrote 06/26/2018 at 08:52 point

Beautiful design, illustration, photos.  I like the brass brads, 3D circuit assembly, and common transistors.  Nice tangible aesthetics.  Your DTL cardboard logic pads make me wonder if a computer (diode-logic) could be succesfully built from a crystal rock collection acting as point-contact diodes.

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Dr. Cockroach wrote 06/26/2018 at 10:02 point

Thank you Lee and you have planted a seed for me to try out. I have some raw radio crystal material put away so I might just try to make a inverter gate to see if it would work. Maintaining contact will be a major issue :-)

Oh, check out my other projects. They all use the brass fasteners one way or another and I love working with cardboard :-)

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TheThriftstoreHacker wrote 04/25/2017 at 23:30 point

Do you think moisture/humidity would be an issue with cardboard? 

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Yann Guidon / YGDES wrote 04/26/2017 at 00:32 point

It might not work well underwater...

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Dr. Cockroach wrote 04/29/2017 at 17:33 point

As long as this project is indoors in a controlled environment I don't see a problem for a couple of years at least. I figure that if I wanted to preserve the finished project then I could spray a nonconductive coating to seal it later.

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TheThriftstoreHacker wrote 04/25/2017 at 18:58 point

Cool idea. Now i want to try it with a Lego.

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Dr. Cockroach wrote 04/25/2017 at 19:01 point

Not a bad idea :-) I say go for it :-)

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