Atari Video Card

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This topic contains 4 replies, has 2 voices, and was last updated by  8bit-Dude 5 days, 8 hours ago.

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  • #209

    gp61
    Participant

    Hello,
    I was wondering if (as soon the final hardware will be ready) you can add a external video card for Atari XE Line of Computer in the Library.
    Please tell me exactly what functions need to be implemented for API, so I will include in my hardware drivers by default.

    Best Regards,
    Gianluca

    #218

    8bit-Dude
    Keymaster

    Hello Gianluca!
    Can you please explain to me what you mean by “external video card”? I have never heard of such hardware…
    Cheers,
    Tony

    #228

    gp61
    Participant

    Hello!
    I am designing a videocard to use with Atari with my ABEX Extender https://github.com/gianlucarenzi/abex.
    At the moment I have two card already designed: a UnoCart Compatible and an expansion memory up to 1024K (can be more if needed).
    https://github.com/gianlucarenzi/abex-megaram for the 1Meg Expansion (it uses the various pokey PORTB expansion bit tables)
    https://github.com/gianlucarenzi/abex-duocart for the UnoCart compatible card.

    At the moment I am building a virtualization mode for atari800 emulator who is emulating the $D5xx access to have access to a videocard with some basic commands. The processor on the videocard is capable of 320×240@256 colors (palette) @ 50Hz. I was thinking (as the memory on board has 192k) having two framebuffers plus a 32 sprites 32×32 pixels (256 colors shared the palette with the screen). If the screen is not bitmapped, the tile mode can be used. Each tile has to be 80×60 pixels, and up to 16 tiles. In that case the tile can be transferred using 4.8k each, so with a very little cpu access to transfer 224 bytes every transfer. Maybe some scrolling can be made. At the beginning I was thinking to have a sort of V9958 emulation mode because it can have 192K as expansion, but I did not found any valuable example using that card on the 6502… So I opted to have a my personal implementation of the video card.
    The processor is a STM32F429I running at 180Mhz with FreeRTOS. Actually it can manage the PHI2, R/W, CCTL, DATA and ADDRESS Lines fairly easily in a task and a second task to manage video output.
    If you give me all details used in your library, I can optimize my code to fit the Unity Library… Maybe it can be done almost easily.

    My personal email is: icjtqr@gmail or gianlucarenzi@eurek.it (job)

    Please let me know,
    Regards,
    Gianluca

    At the moment
    The biggest issue is the transfer of the video data (sprites, backgrounds) in a very small window (224 bytes each transfer).

    #229

    gp61
    Participant

    Just a quick note: is your project opensourced?
    In that case I can add the specific functions for Atari with my card and not using Player/Missile and ANTIC stuff to generate video output…

    Regards,
    Gianluca

    #230

    8bit-Dude
    Keymaster

    Yes it is opensource, the repo is here: https://github.com/8bit-Dude/8bit-Unity
    The installer contains these source files, related assets, and the cc65 compiler.

    Regarding your project, I would recommend that you create support directly into cc65. There is a driver system for memory expanders and such, check this out:

    https://www.cc65.org/doc/atari-5.html

    There are few drivers for the Atari currently, compared with the c64:

    https://cc65.github.io/doc/c64.html#ss7.1

    If you write these drives, then both cc65 and 8bit-Unity will be able to use them!

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