Atari 7800 Graphics RAM/ MMC# for A7800?

[Ecernosoft]

Hi!

I was wondering if Graphics RAM was possible or a new mapper for the atari 7800, 2600, or 5200, with more banks. Maybe, on the 7800, would it be possible to have 16KB of RAM located at $8000-$8FFF, $A000-$AFFF, $C000-$CFFF, and $E000-$EFFF for HDMA (holey dma) sprites/ backgrounds? Let me know.

 

(PS. if anyone has POKEY source code or bankswitched source code (not as a file, just the program in "text" (uncompiled) form), please post it below! I couldn't figure it out. )

[Mord]

If nothing else was available I suppose you could always use 16k ram at $4000-7FFF. Put your graphics bank in say $6000-6FFF then leave $5000 and $7000 banks filled with zeros.  Would allow you to fake some holey dma that way.

[Ecernosoft]

Well, then just do the same with $8000 and use holey DMA right?

[Ecernosoft]

On 5/22/2022 at 5:40 PM, Mord said:

If nothing else was available I suppose you could always use 16k ram at $4000-7FFF. Put your graphics bank in say $6000-6FFF then leave $5000 and $7000 banks filled with zeros.  Would allow you to fake some holey dma that way.

Well, then just put the RAM at $8000-$AFFF and use holey DMA right? OR, develop a special chip with RAM at $8000-$8FFF, $A000-$AFFF, $C000-$CFFF, and $E000-$EFFF. That way, you get the full 4 banks of tiles.

[Mord]

You could likely do that sure but it would require someone with the skills and resources to program those special chips and the like. So as I said, if nothing else was available, then you could always abuse a ram chip at $4000.