ABBUC Hardwarewettbewerb 2025

[CharlieChaplin]

Hier gibt es die offiziellen Regeln des Hardwarewettbewerbs 2025:

https://abbuc.de/aktivitaten/hardware-competition/

[ScreamingAtTheRadio]

Hello everyone! Apologies for the English-only post. This is my submission for this year's contest:

Der Dateianhang IMG20250629123654.jpg existiert nicht mehr.

The DecentCart2350 cartridge is a new multicart for Atari 8-bit computers. What? Another multicart? Don't we already have plenty of these?
Well, yes, and those carts are all great in their own way. I have my reasons to make my own though:

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First, because I wanna. I really liked the idea of Raspberry Pi Pico-based cartridges like the A8PicoCart and many others on other platforms. The idea that we don't really need an FPGA and can just race the bus with a microcontroller is very, very nice: microcontrollers are a lot easier to program than an FPGA, the learning curve is way gentler, and there's plenty enough power to drive something like this.
Second, I had this idea that a cart with a screen could push the envelope, provide a better experience and open up a whole new range of possibilities. Just the idea of having the label of the game you're playing displayed on the cart is a very nice enhancement to the multicart experience in my opinion...

Third, this cart is entirely open source: the PCB design, the enclosure, the firmware, all of it is under a permissive license. I'll be selling carts myself of course, but you can absolutely build your own, hack the firmware and contribute changes and fixes.
The DecentCart 2350 is based on a RP2350B microcontroller chip, with 16MB of flash memory, a micro-SD card port, a micro-USB port for firmware updates, and all the lines going to the Atari motherboard are behind level shifters doing the 5V to 3.3V translation in both directions. It also has a debug port and an ECI port, which opens up all the PBI peripheral features with a small additional connection at the back of the cart. The screen is a 320x170 color screen that's the largest that I could fit into the part of an Atari cart that sticks out of an XL computer. the enclosure is a custom design I made in FreeCAD that is the same size as a standard Atari game.

There's still a lot of work remaining on the firmware, but the hardware is finalized. The cart can read signals on the Atari bus, read from the SD card and display anything on the screen.

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This cart, with two cores, DMA and 12 PIO state machines, has plenty of computing power. Racing the bus is essentially doable with just PIO and DMA, leaving most of the two cores free to do other things. You can imagine having heavy calculations performed on the cart and the Atari just picking up the results through the magic of DMA. Imagine what you could do by pointing the screen memory to an address space managed by the cart, which can dynamically fill that space with a view of a complex 3D world. The Atari doesn't have to do any of those calculations and can just handle controllers and keyboard interaction. The cart is then like a GPU, and the Atari just sees as the content of the video memory whatever the cart computed on its own.
Another cool application could be a kind of "rich text" mode where the text layout and proportional font rendering is done on the cart, and the Atari just has to pick up the rendering, by reading the memory for what is to it just a 320x200 high res mode.
You could also manage huge game maps on the cart, have large software sprites, "hardware" zooming and rotations, etc. You don't really get new graphics mode, but you get more powerful versions of the existing ones.
The extra display on the cart could also be used as a second screen, and display a map, or work as a HUD.
Of course, this is still speculative and remains to be implemented, but the potential is here, and over the next year, I'll have plenty of time to demonstrate those features.
Let me know if you have any other suggestions for what could be done with this hardware... With that, thanks for reading, and please vote for this...

I posted a video here: https://www.youtube.com/watch?v=o-sEndb4mEI

[cas]

If the microcontroller has RAM available, a RAM paging option would be great (to use the RAM in the RPI as memory expansion).

I also like the GPU idea, where the Atari writes high-level graphics commands into some RAM, and the RPI renders the pixel into the ANTIC screen memory.