June 18, 2019 at 10:26 am #209
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.
GianlucaJuly 13, 2019 at 9:04 am #2188bit-DudeKeymaster
Can you please explain to me what you mean by “external video card”? I have never heard of such hardware…
TonyJuly 13, 2019 at 3:24 pm #228
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 firstname.lastname@example.org (job)
Please let me know,
At the moment
The biggest issue is the transfer of the video data (sprites, backgrounds) in a very small window (224 bytes each transfer).July 13, 2019 at 3:48 pm #229
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…
GianlucaJuly 14, 2019 at 1:09 am #2308bit-DudeKeymaster
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:
There are few drivers for the Atari currently, compared with the c64:
If you write these drives, then both cc65 and 8bit-Unity will be able to use them!
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