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Project Veronica


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Just got my cart, beautiful stuff. Really great idea. I plan on seeing if I can wrap a CC65 library around it.

 

I do think that a PBI implementation would have been more useful. It makes me sad I can't use it with the dragoncart, it would be absolutely perfect for a TCP stack. Guys - next rev drop a cs8900A on there :)

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  • 3 weeks later...

I now have a Veronica 2.0 Cart and I have a question. Which way do you plug the cart into a 130xe cart chips facing up or Cart Chips Facing down? I saw which way the version 1 was plug in. but I do not want to destroy the cart by plugging it in wrong. I have destroyed two carts in the past because there were not instructions on how to install. As nice as this cart is I would have liked to have seen on the solder mask which way to install. But still a very very nice cart. and I want at least one more maybe more.

 

Stephen J. Carden

http://www.realdos.net

 

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  • 4 months later...

I tried to wrap my head around possibilities to program Veronica but still can't really get what RAM (banks) go where when those bits are set.

 

Is there any better description (or maybe some graphic representation) of what goes where with which bits set?

 

Are RAM banks superimposed on top of Atari RAM or is Atari RAM swapped with Veronica? (I suppose the former but am not sure.)

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Are RAM banks superimposed on top of Atari RAM or is Atari RAM swapped with Veronica? (I suppose the former but am not sure.)

 

Superimposed.

 

Atari CPU has its own 48K+ RAM, Veronica CPU has its own 64K RAM, and the two share 64K of shareable memory. That 64K of shareable memory is split into two 32K halves, such that one is always visible to each. They can swap, but the Atari and Veronica never see the same 32K halves at the same time. Each 32K half is in turn split into 16K banks, and each side independently chooses which 16K it views from its 32K half.

 

From there, Veronica always has its 16K view mapped at either $4000-7FFF or $C000-FFFF. Atari has its 16K view split across the two 8K cartridge windows ($8000-9FFF and $A000-BFFF). Both of which can be toggled independently, but not positioned independently.

 

The main limitations to keep in mind: the 6502 and the 65C816 never see the same memory at the same time, the 65C816 always has its window enabled, only the 6502 can switch banks, and if you want to be compatible with V1 hardware you have to make sure the 65C816 is clear of its window when bank swap occurs.

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  • 3 years later...

Bob pointed me towards Veronica, I watched the YouTube video, why not make it a PBI/ECI device and load in the driver and/or vbasic?

 

Also youd gain access to the halt line which Atari made for using external CPUs like the Z80 and I just found a memo that they were also looking at IBM card with an 8088 on it, so why not have the ability to switch to either or and utilize more of the available lines from the pbi/ECI?

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