AtariAge member electrotrains released his A8Pico Cart Project a few days ago on GitHub, and I've been busy integrating that into my design. Here's where things are at presently...

Everything is now 100% routed.

 I made a lot of changes on the component placement in the PCB layout, making it far more conducive to routing traces between components. This also altered the board shape slightly.

On the R-Time 8 aspect I changed to a larger battery same as was used on the original ICD variant back in the day (CR2430). I also have the power for this and the SDrive as an 'Always ON' situation taken from the 576NUC+ 5V Stand-By power connection, which is available from the internal SIO header. This means that so long as the NUC is plugged into wall power, irrelevant of whether the 576NUC+ is turned on, the R-Time 8 will run from the 5V power supply and not from its battery thus greatly extending the battery life. I wouldn't be surprised if the battery lasts for at least a decade with this setup.

Because the SDrive also gets its power in a similar aspect, drive assignments should be retained between power cycles.

Over the next couple of days I'll be double checking the PCB layout and schematics, and if all looks solid I'll be pressing the BUY button at JLCPCB soon after. Then when those sample boards arrive we'll see how or if I screwed up on something - always exciting.

-Michael

Update 9/13/2023:  I never pressed the buy button on this board version. After running some breadboard tests, and because of discussions in the A8Pico Cart AtariAge thread about protection circuits, and a change in direction on the SDrive aspect, everything changed. So much so, that an entirely different PCB layout was required, with the first sample PCB based upon this change having now been manufactured and awaiting assembly and test.

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Robin Edwards (electrotrains at AtariAge) has been at it again, and recently starting talking about an entirely new version of the 8-bit UNO Cart, only this time based upon a Chinese clone of the Raspberry Pi Pico. On this go around it has no removable media such as what the original UNO Cart utilized via its micro-SD Card, and instead it stores its files to an onboard 16MB of non-volatile Flash RAM, updated via USB.

Note: The Chinese Pico Clone is not a drop in for a real Pi Pico, having a different pin-out, as well as more I/O and more Flash RAM. The clone was required for this A8 version.

So I started thinking (always a dangerous thing), and decided to make something akin to an All-In-One daughter board module for the 576NUC+ project which would incorporate this new Pico Cart idea, along with several other very useful peripherals.

And here's a sneak peek as to what that may look like...

Currently I've assigned the moniker RPSX to it, which stands for the 4 main aspects contained within this module.

• R = R-Time 8
• P = Pico Cart
• S = SDrive
• X = XRAM (1024K extended RAM)

The Pico Cart does have ATR capability, but just like it's UNO Cart cousin this has some limitations, such as not being able to launch a CAR and an ATR at the same time. So it rules out doing something like launching Basic XE as a virtual banked cartridge and still being able to load and save Basic XE source files to and from the built-in file space. Hence the reason for also incorporating the SDrive.

BTW, the default 576NUC+ platform has absolutely no inherent banked cartridge support what-so-ever.

And while I was at it, I decided to give it the full 1MB of RAM, as well as a battery backed real time clock, making this a very well rounded upgrade for the 576NUC+.

Now on the surface it may look like I have this all figured out, but I presently don't have a clue as to what I/O pin goes to what on the Pico board until such time that the A8Pico Cart documentation gets released to the public, something that I have no idea of when that may happen.

Anyway stay tuned, and hopefully we'll see this project continue to come together.

- Michael

Note: The development on this project continued and got merged back into the 576NUC+ topic. Take this LINK to read more.