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Recommended: Gigatron

a computer w/o a microprocessor


KIM Uno: a DIY clone of the KIM-1

How to get, or build a KIM Uno...


KIM Uno is open source hard & software. Given that I'm packaging together the work of others (the original KIM-1 ROM, but also the 6502 emulator of Mike Chambers) it would be pretty bad taste to do anything else.


  • August 2022: 900+ kits have been built so far! Thanks for all the nice feedback.

  • Alternatively, and easily, you can download the Gerber files and send them off to a PCB manufacturer like for a few dollars, and obtain the other parts as described below. 

Option 1: Contact me


Please drop me a note through the Contact page if you'd like one:

Kit - PCB plus all parts, and pre-programmed Pro Mini, but without USB cable: $17.50. The plastic enclosure shown in the right-hand picture above is an additional $8.

Shipping worldwide is $15, covers up to 2 kits. Up to 4 kits: add $5 to that.

I'm sorry, shipping from Switzerland (where I live) is very expensive. Following Option 2 below is cheaper. Getting the few required parts yourself is simple, ultra-cheap and thus -- what's the risk?

Because I lack time, I had to stop making KIM Uno kits. Regrettably.

But! Someone is making and selling the kit on eBay. Which is totally legit, it is Open Source Hardware. So 'option 1' is now to look on eBay. I have no connection with the vendor, but many people bought from him so I feel very comfortable mentioning it.

Before you build the kit, please read the Building Instructions. There's one step you do not want to miss.

Option 2: Produce your own


There are only a few parts to the KIM Uno, and all of them can be bought very cheaply through eBay, Aliexpress and the like. Here is a list of parts:


  • Arduino Pro Mini. These are produced in slightly varying formats. The three below fit the Uno board:

The only important things: (1) pick the 5V, not 3.3V version of the Pro Mini. And choose a version that has the two pins for A4 and A5 as shown in the green circle. A6 and A7 (red circle) can be ignored altogether.

  • Two 3461BS 7-Segment-LED blocks.
    Long description: "0.36 inch" "Common Anode" "4-digit" "7-segment LED Digits" "with decimal point".

  • Eight 1K resistors, plus three 4.7K ones (these can be anything from 2K to 4.7K really).

  • 24 keys, standard 6 by 6mm PCB tactile switches.


  • The PCB can easily be ordered online from, Seeedstudio or any other PCB manufacturer. The Gerber to be sent is in the download section. Cost as of September 2020 was $10 for 5 boards. And you get a $8 rebate coupon from them thrown in. It really costs next to nothing, just give it a try!

3. Useful extras:


  • to use the serial terminal, a TTL USB-to-Serial cable is the best option. They cost about $2.
    That cable can be used as a power supply too. Look for "PL2303 USB-Serial cable" on Aliexpress.

  • Other power options:

    • a power switch on the top left of the KIM Uno allows you to connect a 5V power supply,
      or a battery box with three AAA batteries (the 4.5V is fine),

    • a power switch on the top right on the KIM Uno allows you to connect a 9V battery,
      or any power source from 6.5 to 12V.

  • If you want to tinker with the firmware, use the above-mentioned cable as an Arduino programmer.
    In that case, you have to press the Mini Pro's reset button during compilation in the Arduino IDE and release the reset button after you see the message "Uploading..." appear in the software's status bar.

  • If you have a 3D printer, a custom case design can be downloaded here.


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