Kevin Santo Cappuccio Hacks the Jumperless V5 Into the World's First Breadboard to Run Doom

Kevin Santo Cappuccio, creator of the Jumperless wireless solderless breadboard family, has shown off a new ability for the latest-generation incarnation of his device: the ability to run id Software's 1993 first-person shooter Doom.

"I'm sure you’ve seen my original Doom 'demo,' which is pure lies," Cappuccio explained to us via email. "I just hand drew each frame in [Adobe] Photoshop, img2cpp'd it into an array, and had it play them one after another, lame. So when people mention that Jumperless V5 plays Doom, I kinda felt bad knowing it was fake. So yeah, this is Doom For Realsies."

We first saw Cappuccio's Jumperless back in March 2023, and it took a little convincing to be sure it wasn't a joke. The idea behind the project: taking the solderless breadboard to its illogical conclusion by also removing the jumper wires. It's no joke, though: the Jumperless works by connecting the tracks of a solderless breadboard using crosspoint switches on a PCB hidden underneath — allowing connections to be made programmatically rather than by hand.

By the time we went hands-on with the device in June last year, Cappuccio had considerably expanded the scope of the project. Now powered by a Raspberry Pi RP2040 microcontroller, the Jumperless included RGB LEDs behind each addressable row of breadboard connections — and the latest incarnation, the Jumperless V5, moved to the bigger and better RP2350B to control an RGB LED behind every single hole of the breadboard.

In doing so, Cappuccio effectively created a breadboard-slash-microcontroller development board that doubles as its own display — and demonstrating that led to the "pure lies" version of Doom. "I was chatting with Guy Dupont a week ago, and he’s working on a project that involves running Doom on an RP2040 for some other thing," Cappuccio explains. "And he made me aware of doomgeneric (basically Doom but someone organized the code to make it easy to work with) and shared some of his working WIP [Work In Progress] code. I didn’t just get nerd-sniped, I got […] nerd-nuked from orbit.

"I’m actually not using that now, I’ve scrapped the code and started over like five times (and probably will again). Now I’m using rp2040-doom-LCD, with some git [trickery] to merge RP2350 support from the repo it was forked from and treating the Jumperless as just another model of display. The game sends scanlines and I shove them into an array, and when the frame's finished, I use the ws2812 PIO code from pico-examples to send it to the breadboard LEDs, they're just a string of 445 XL-1010RGBC-WS2812Bs (I actually split it in two on the last rev for better frame rates)."

"If I'm gonna make this actually somewhat playable, I'm also need to come up with some kind of shader that makes walls and enemies visually pop so they don’t turn into a mushy blur on a (weirdly spaced) 14×30 display," Cappuccio adds. "I'm still working on getting input from the rest of the Jumperless's hardware, and decide what exactly the clickwheel and probe are going to control."

Cappuccio has posted the project's source code, dubbed "joom," to GitHub under the reciprocal GNU General Public License 2. "I really need to start over and make this work with Earle Philhower's arduino-pico which is what the rest of my code is written in (and both Jumperlesses are officially supported!) and what I’m most comfortable writing," he notes. "Right now it's raw pico-sdk and cmake which I barely understand, having a whole meta-programming language on top to compile your actual code is mind bending."

The Jumperless V5, now officially Doom-compatible, is available to pre-order via Crowd Supply now at $369, with hardware scheduled to ship in April.