graphics-gremlin
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schlae
Open source retro ISA video card
I'm trying get some old floptical drives running on several ISA-based platforms I have been working with. I came across this project and I'm glad to see someone is working...
Hello! Thank you for a great project, published under opensource license! Could you please add a file `LICENSE` or `COPYING` with a license text, so the forks (like https://github.com/yeokm1/graphics-gremlin-hdmi) wouldn't...
The timing for CGA modes, 640x200 or 640x400 implemented with scan doubling, seems to be a bit off. The picture on my VGA monitors appears to be shifted left significantly....
https://youtu.be/1qpRQW7TCzo More info: https://hackaday.io/page/14228-improving-the-graphics-gremlin-project
The FPGA byte code from November 20, 2021 (the latest) produces memory errors at certain memory addresses in both MDA and CGA modes. It also results in memory/screen corruption in...
[Olivetti M24](https://en.wikipedia.org/wiki/Olivetti_M24) had mostly CGA compatible display adapter with several enhancements: * The display resolution was 640x400 * Standard CGA graphics modes used scan doubling, very similar to Graphics Gremlin...
I have started a new development branch to implement the graphical mode of the hercules. As Hercules is actually an improved MDA, I have chosen to take this as a...
MDA (70Hz VGA compatible) on some boards has issues with the attribute byte getting corrupted by the previously-read character byte. This shows up as spurious underlines, inverse video, etc on...
These all appear to be timing issues. Investigate the relationship between the display enable/vsync bits in the status register and the sequencer.
The arbitration logic between the SRAM, the CGA pixel engine, and the ISA bus isn't quite intelligent enough and triggers a lot of CGA snow--more than the original card.