Gigatron on an FPGA

Using, learning, programming and modding the Gigatron and anything related.
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Gigatron on an FPGA

Post by menloparkinnovation » 11 Sep 2018, 03:13

Hi, I have created an implementation of the Gigatron on an FPGA.

The project site is at

Thanks, and happy hacking.

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Re: Gigatron on an FPGA

Post by marcelk » 15 Sep 2018, 05:27

Congratulations, you're the first to report a successful recreation in FPGA!

For those who missed the pictures/ directory on GitHub:

The attachment hardware_wiring.jpg is no longer available
hardware_wiring.jpg (98.76 KiB) Viewed 499 times
signon.jpg (102.58 KiB) Viewed 499 times

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Joined: 01 Nov 2018, 12:02

Re: Gigatron on an FPGA

Post by bmwtcu » 20 Nov 2018, 01:27

menloparkinnovation wrote:
11 Sep 2018, 03:13
Hi, I have created an implementation of the Gigatron on an FPGA.

The project site is at

Thanks, and happy hacking.
Thanks for posting your design. It was very helpful in putting together my own Gigatron FPGA. I've been working on this for the past 6 or 7 weekends. It's still a work in progress, but I'm declaring partial victory now that it boots!!!

Gigatron.jpeg (216.69 KiB) Viewed 312 times
1. Re-learn Verilog. My last FPGA design was in 2006. I really need to work on testbench creation, but wouldn't you know it, the Gigatron is so simple that my simulation candidate booted before I could get a stimulus file put together!
2. Upcycle as much as possible. FPGA development board is actually a satellite modem from the RF bone pile that was being tossed. The FPGA is a Xilinx Kintex-7 with ~160k Logic Cells, so plenty of Distributed/Block RAM and room to grow. It also is supported by the free Vivado WEBPACK, so I didn't have to spend any money on development tools. Fortunately the math for 3.3V R2R DAC worked out and were resistor values I already had in my toolbox. Cables and LEDs were all salvaged together with the board.
3. "Upgrade" to 64k SRAM.
4. Direct drive a TFT display? Have to research whether this is possible.
5. Along the way, ROMv3 showed up and I just had to add that too.

What works:-
1. Blinkenlights
2. VGA display

What needs work:-
1. Right now, I'm trying to assemble a controller with a 74LS165 PISO shift register chip and some pushbuttons I salvaged before I can test input.
2. I don't have an R2R SIP in my toolbox, and I don't quite have enough room on my salvaged perfboard to build one from scratch. I do have a boatload of resistors and caps, as well as a PAM8403 Class D amp and salvaged speaker that I was going to use. I just need to find a perfboard to build it up on. I might just cave and break open a new perfboard so I can work on the audio DAC over Thanksgiving.
3. Even with using distributed RAM instead of block RAM, I'm comfortably under 25% utilization. With all that room left over, I might also have to look into implementing keyboard interface/Pluggy McPlugface too. ... core_opt.v
4. Figure out how to port Floppy Bird to the Gigatron. My last assembly program was in 1996.

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