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


WOZ monitor on TTL

TV Typewriter is just a stepping stone and by now we also have a small monitor program. To stay in retro style, this time we didn’t invent our own but we faithfully ported the Apple-1 built-in monitor program to the TTL architecture: the infamous Woz Monitor!

Now you can directly inspect memory locations, write to them and execute code on the hardware itself.

Steve Wozniak’s original is 254 bytes, our version is $254 bytes. About half of that is for terminal output, or character printing. The Apple-1 had dedicated hardware for that, something we’d consider cheating of course [tongue in cheek].

Source and GT1 object files are available in GitHub. A nice user manual for the original is here. With this step, all original Apple-1 firmware has been ported to the Gigatron 🙂

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.

Extensive customer review

A meticulous and enjoyable explanation, assembly and running of the system by [youtuuba]. There isn’t much detail missed. Thanks P. for making this documentary and sharing your thoughts!

Duration: 1h17m

The 8-Bit Guy

Before refurbishing his cat house, the 8-Bit Guy made time to do an episode on our kit.  Needless to say this we think this is his best episode ever 🙂 . Approaching 300,000 views so far, but 100 of these must be our own reloads. Thank you David and we’ll get you an updated Snake later that doesn’t require color vision.

Duration: 12m15s

Gigatron as TV Typewriter

The video shows how an Arduino can be hooked up and pretend to be an ASCII keyboard. No EPROM change is needed. After powering the Arduino, it takes over control by resetting the Gigatron, navigating the menu and starting Loader. It fakes game controller signals to do that. Then it pushes a tiny precompiled Terminal program into the RAM. From there on, it sends simple ASCII codes which the board dutifully displays. This is step 1 towards interacting with the system for direct hacking.

The source code for the sketch is in GitHub. Hookup is with 4 male-to-female jumper wires, as explained on the Tutorials page.

Edit: The Arduino in turn can interface with a keyboard. Here an example with a PS/2 keyboard, using a standard library to handle the protocol.

The Arduino is a bit of an overkill here. A simple ATtiny85 will do the job just as well.

Gigatron kits are shipping!

Double good news today. The first good news is that we will be speaking about Gigatron at the upcoming Hackaday conference on May 26 in Belgrade. We’re super excited that our talk was accepted, and hopefully this event is a chance to meet with many of you. The second and even greater news is that our supplier has sorted out their delivery issue. We reported about that hiccup earlier this month. This means that now we’ve all parts in-house for a first batch of kits. Gigatron is ready to ship, and we’re open to take orders!

Ordering details under “Get One!” 

Updated grammar using EBNF

With ROM v1 done and arrival of the last kit parts confirmed for this week (yeah), now is the time for chores. The syntax I used for writing the apps has some rough ends. It was grown bottom-up, hand in hand with the GCL-to-vCPU compiler, while vCPU was still evolving. As I’ll need a new compiler for the Arduino interface anyway, why not fix what can be fixed? So now here is a formal EBNF definition of the updated notation, or call it a language if you wish.

There is a great online visualizer that turns these grammars into easy-to-understand railroad diagrams. I’ve always liked these since studying the “Pascal User Manual and Report” in my first year at college. A webpage with all diagrams sits here on HaD.

GCL will never look pretty, but it at least it isn’t Perl.

Small hiccup, but almost there!

With great anticipation we received our last parts for the batch last week. Panic ensued when we discovered they were of the wrong type. Not a few, all of them… Did we place a wrong order? Frantic discussions with the supplier followed and yesterday it became clear: they messed up, apologised, and they are now sending us a new batch. We expect the total impact will be a two-week delay. Bummer, but at least we didn’t lose any money on a stupid mistake.

So please bear with us a little bit longer, soon you will be heating up your soldering iron!