GameTank - A fully open source 8 bit console

[CShaffer]

Hiya folks- I made this 6502-based game console because I didn't find it very compelling that platforms like Pico-8 could only exist in emulator form.
The GameTank is a bottom-up design I arrived at by experimenting with 74-series logic on breadboards, Ben Eater style.
I didn't use an FPGA because I wanted the system's baseline definition to be physical rather than as configuration data.

It takes its software on cartridges, uses 9-pin controller ports, and outputs composite video. The resolution is quite small at 128x128 but the specs are less "intentionally limited" and more that the design process naturally ended up there and had enough room to have fun with.

Besides the hardware I've also put a lot of development into tooling because game consoles are more fun when other people can make games for them. Though I do also spend a lot of time developing games for it myself, having been a hobbyist gamedev longer than I've been a hobbyist hardware designer.

Initially I focused on "distributing" the system by publishing thorough documentation on how to assemble it along with the board files and parts lists for a 99% through-hole build. Enough people asked about getting a prebuilt version though, that I also spun up an SMT version for robotic assembly. It also turns out to be much cheaper per unit to build them this way, and a lot of the appeal of the system is retained even if you haven't hand soldered it yourself. (Though a few people have enjoyed doing that already!)

So right now I'm trying a Crowd Supply campaign to get a big batch of these made; for people who are interested in programming, hacking, or otherwise playing around with the real hardware basis for this platform:
https://www.crowdsupply.com/clydeware/gametank

The bundle on Crowd Supply includes the console, controller, cables, printed manual, game cartridge, blank cartridge, and cartridge flasher. Out of the box it includes everything needed to play with and get started developing for it.

Full docs, specs, and other info can be found at the project website: https://gametank.zone

Thanks for reading!
-Clyde

[PlainName]

This is a stunningly good project for a single person, covering every possible base (the website even having playable demos of the games). 

[Kean]

Yes, impressive work!

Good luck on the FCC/CE testing.  I'm interested to hear how that goes.

I am also interested in why the FFC connectors were not aligned between top and bottom boards.

[CShaffer]

Thanks!

The FFC connectors not being aligned was originally an accident. "I copy-pasted the coordinates so they should line up exactly, right?"
It stayed like that because I found that the offset made the FFCs more positionally stable when I tuck them to fit inside the enclosure.
(...Also routing them on both boards took forever and it hadn't caused enough problems compared to other things I was solving)

I'll follow up with what I learn from the FCC/CE testing. I just finally got the latest mainboard revision back from PCBWay that I ordered in December, and can now assemble the representative sample to send in.

[CShaffer]

Good luck on the FCC/CE testing.  I'm interested to hear how that goes.

Well, the good news is my cartridge flasher passed first try. The console produces conducted and radiated emissions above the CE limits so I'm drawing up a board revision that applies better high frequency practices.

Most of the logic is 74HC but I use a 74AC counter to distribute the clock and apparently I'm using that for some random OR gates. Swapping the main clock divider to HC produces some glitches so I'll try rearranging my traces (and ribbon cable pinouts) to keep those as close to ground as possible.

Hopefully the system works fine after swapping the 74AC32 to 74HC and then I just don't have to worry about those as much.