Gigatron fully open source

The Gigatron TTL computer is now fully open source! The source code had been open source (BSD license) since the beginning of course. A while ago, we published the design files for the printed circuit boards, both for the Gigatron and for Pluggy McPlugface, the PS/2 adapter.

We have now also made the full Assembly and User manual available online, under a CC-BY-SA license. The assembly manual contains the list of components, which is now also available separately as a Bill of Materials under the same license.

These files should enable to you make your own Gigatron. The only part that is no longer available is the custom made wooden enclosure.

If you decide to build your own Gigatron, we won’t provide support. But we do encourage people to go down the rabbit hole 🙂


Almost a year ago, we had sold over 500 Gigatrons, much to our own surprise. Since then, a lot has happened. We now have 6502 emulation and the Gigatron can run Apple-1 code, such as WozMon. We have BASIC running and there’s a great BASIC compiler, opening the way to create great games. Looking back on the original goal to play tic-tac-toe on a LED matrix, we are super chuffed that we have a system running BASIC that feels like an actual homecomputer from decennia ago – still without a microprocessor.

And today, Gigatron #1000 has found a new owner! Thanks to everybody for making happen what we could not have dreamt of when we started!

Future of the Gigatron

We are nearing the end of our current stock of Gigatrons. I suspect stock will last for a few months from now. We have decided to stop selling kits once our current stock has been sold. For us, the Gigatron was always about inventing new things, understanding technology, designing, fine tuning, tinkering, and also about meeting like minded people. Making it into a kit had its own charmes. Packaging and sending out kits resembles a plain job too much, but was needed to create a community of people that would also want to design, understand and tinker.

That community now exists, and wonderful things have already come from it, both hardware and software. So we will stop selling and providing support in a few months. Does that mean you can no longer get a Gigatron? No, you still can, because the PCB layout, the schematics and the software have all been open sourced. The only thing you probably cannot get is the wooden case that we had tailor made for the Gigatron. Somewhere in July or August, the assembly manual and more will published on an open source license as well. We hope the Gigatron will live on!


Recently we passed a milestone that far surpasses our stretch goals. Originally we said we’d be content if were to ship 50 kits and call it a day. Our tongue-in-the-cheek stretch goal was 200, because that’s the number of Apple 1’s ever produced. Now, a little over one year later, more than 500 Gigatron kits have shipped to over 40 countries. Recipients include the headquarters of Facebook, Google, Microsoft, Apple and … ARM. Thanks to all buyers for your greatness, kindness, feedback and support! It has been a blast for us, and we’re not done tweaking yet…

New 8-Bit Guy review and the Superconference

The 8-Bit Guy’s new review of Pluggy McPlugface (our PS/2 keyboard adapter), Tiny BASIC v2 and the new games in ROM v3.

It’s the same as we exhibited at the Hackaday Supercon last week. Speaking of which, the conference badge was screaming for this hack:

It’s in fact a cycle-exact emulation of the TTL circuit based on gtemu.c. The emulation runs at 3 frames per second instead of 60 frames. It still manages to play Racer. Typing in Tiny BASIC v2 goes remarkably well.

Full circle

Today, a circle closed at the Centre for Computing History in Cambridge, UK.

How? Well, one week before this project started on Hackaday, I was at the Computer History Museum in Mountain View, US, and jokingly posted the following remark on Facebook:

That’s an original Apple-1. The Apple-1 next to the Gigatron is a beautifully done replica. It’s fully functional, complete with cassette interface. The PCB is drawn in the same way and the chips even have 1970s date codes on them. It’s on display in an operational state. I could play around and type commands in the original Woz Mon to verify that the Gigatron version works the same.

Many thanks to David Williams for the great opportunity!


Oscar brought his Gigatron, with our prototype keyboard adapter and Tiny BASIC, to VCF West 2018 at the Computer History Museum in Mountain View. He came back with the “Judge’s Special Choice Award”. How cool is that! Utterly flattered…

Thanks Oscar and thanks VCF!


We’ve recently celebrated a dream milestone: there are now more Gigatrons out there than Apple-1’s ever produced!


It’s a-LIFE

We are still a bit short on tutorials and tools to make the Gigatron more accessible for hacking. But that hasn’t stopped some brave souls from figuring it out for themselves. Phil made a great emulator that runs realtime in a browser, in javascript. At67 wrote a stand-alone vCPU assembler to go with his own emulator. Some started to make their own operating system. One buyer announced plans to rewire the instruction decoder in order to get just the right 8-bit instructions for the application he has in mind. Drogon wrote some GCL, made a ROM file, stripped the object code from it, copied that in an Arduino to send it to the Loader and execute it from RAM. Speechless… [Edit: it is MUCH simpler now to do the same today. The tools keep improving every week]

Now is the time to standardise on a file format for vCPU programs. Most hackers will start at the 16-bit programming level because it is easiest. Programs can be loaded into the system with the Loader application, without reprogramming the EPROM.

After some discussion with the emulator guys, we have agreed on a file format for both real boards and emulators: GT1 files.  At67 quickly coded some demos in his vCPU assembler and produced GT1 files for them. These work in his great emulator. But his kit hasn’t arrived yet, so I tested it for him. See here “life3.gt1” and “lines.gt1” loaded on my development board with ROM v1.

It works! We have a standard for exchanging Gigatron programs!

Edit: Check out this video for what is brewing in emulator land. Sprites!


Ozzie build

Woke up this morning and wondered where those new kit orders suddenly came from. It turned out that right at that moment Dave Jones () was building a board in a Youtube live stream with many hundreds of viewers looking on. I caught the last half hour or so. I couldn’t stand the suspense when he was searching for a cable. He didn’t use the manual, skipped all tests, still it worked 1st time. “This is disappointing, there is nothing to troubleshoot!”. Greatest compliment ever! THANK YOU!

Edit: the live soldering turned out to be a prelude to more to come. The Gigatron is now honoured with an official EEVblog episode! We’re truly and utterly flattered.