Lego computer : Digicomp

The digicomp was a mechanical computer sold as a plastic toy in 1963. Capable to count, multiply, divide, depending of how it is programmed.

Direct purchase of the instructions

10,00  -Excl. Tax
The Digicomp was a mechanical computer sold as a plastic toy in 1963, capable to count, multiply, divide, depending of how it is programmed. Here is a functional replica in LEGO Technic.

Preview of the instructions at the end of the article.

This computer  is composed of :
  • Clock
  • Operating Wires
  • Bits (3)
  • Sense Wires
  • Programm
The clock is operated manually. It is composed of two sliders which surround the rotating actuator  wires, its role  is to operate the rotating actuator wires, depending of two variables : the bit-value and the programme.
The grey plate represents a binary digit : a bit It can slide to indicate two values, 1 or 0. The two rotating actuator wires operate the digit. One to move to 0 and one to move to 1 (set and reset). In normal functioning : nothing happens but when a rotating actuator wire is slightly pushed, the clock moves entirely the wire and the value of the digit changes.
The key is to slightly push the actuator wire when the value of the bit needs to be modified The key is this device : the sense wire. It enables the machine to read the programme and the value of bits and allows binary operation. The sense wire is connected to the actuator wire thanks to a fork. If the sense wire moves, the actuator wire moves too.
The key is to allow or forbid the movement of sense wires : thanks to the programme. The red joiner represents the programme. It is a stop for the sense wires. When it is behind the sense wires, the sense wire cannot move, the actuator wire cannot move and the value of the bit is not modified. When it is not behind the sense wires, the sense wire can move, the actuator wire is slighly pushed by the sense wire and the value of the bit is modified.
To understand more presicely, watch the video with an example of program :
The digicomp can be programming for many things, couting, dividing, even playing game, in three bits.

Purchasing the creations or the instructions

You can purchase either the whole creation on the website Buildamoc, or just the building instructions. Regarding the building instructions, you can download one version as a photo sequence for free or buying a other one which looks more Professional with rendering step by step instructions with bill of material at each step.

buildamoclogoWant to buy this creation ? The Digicomp has been indexed to Buildamoc and is for sale. The whole package included the Lego genuine parts, and the Pro rendering PDF building instructions.


Building instructions

Concerning the building instructions, I have took picture during the taken apart, and Kevin William has made the instructions for me with very high quality of image and building including some program to run at the end (count up and down, guess the day…)

Therefore I can propose you a free instruction as a photo sequence, and a for sale one with digital rendering building instructions.

Digital Rendering Building Instructions

Here is the Bill Of Material as PNJ file :

Want to check before if you can build the Lego Computer ? The Digicomp has been indexed to, the website which matchs your parts with mocs !

You can buy the instructions with the following button for 10€. You can also buy other building instructions and get an automated discount. You will get 15% off for 2 PDF, and 20% off for 3 PDF on the total), available for all the instructions for sale on

See it on the shop :

10,00  -Excl. Tax
The Digicomp was a mechanical computer sold as a plastic toy in 1963, capable to count, multiply, divide, depending of how it is programmed. Here is a functional replica in LEGO Technic.

After your payment, you will be redirected to a page for downloading your instructions, and will receive also the link to download by email. Please check the spam box and be patient to receive it. If you have trouble to download your copy of the PDF after payment or open the document, do not make a paypal dispute, please contact me using the contact form. The link to download the instructions expires within 24h. Contact me if you have lost your instructions. Note that you can print it, but not copy or distribute. Thank you for supporting my work 🙂

Here is some preview of the building instructions :

Photo Sequence Instructions

(10) Comments

    The pdf link works good. Maybe a problem with your navigator ? ( download a bit longer, try crigh click, save as)

    I had the original toy in 1969. I learned about binary
    Numbers and simple calculations before I was 12 y.o. good job!

    This is very amazing. You always come up with the amazing things that look complicated and still work perfectly.

    bonjour est ce que il existe un site pour construre en 3d sur l ordinateur.
    merci de me donner un site .

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