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Improving the Graphics Gremlin

Open spark2k06 opened this issue 2 years ago • 11 comments

https://youtu.be/1qpRQW7TCzo

More info:

https://hackaday.io/page/14228-improving-the-graphics-gremlin-project

spark2k06 avatar Feb 05 '23 17:02 spark2k06

looks pretty good although i still need to test it on the real hardware.

one general comment: i'm not a huge fan of renaming mda to hgc because the logic is still mostly copied directly from the MDA schematic in the IBM tech ref. can you keep the MDA names but add hgc_ to all the Hercules signals that you added, making it super clear these are HGC-specific mods?

I think that's right, as soon as I can I'll review all your comments and rethink the code according to your criteria.

My changes are not based on schematics, but on behaviour according to the HGC and Tandy 1000 technical manuals.

On the other hand, I may not have been very careful with the names of the registers and wires, you are free to rename them as you think is clearer for the project.

spark2k06 avatar Feb 06 '23 06:02 spark2k06

I've added new commits to my fork, but I don't quite know how to add them to this pull request:

https://github.com/spark2k06/graphics-gremlin/commits/main image

spark2k06 avatar Feb 06 '23 09:02 spark2k06

I add bitstream 3 in my repository, initially with Adlib.

Adlib is based on @jotego's JTOPL2. Others can be added later, e.g. CM/S at the same time in the same bitstream.

https://github.com/spark2k06/graphics-gremlin/commit/a3fc3b24a1f9e28c80c948d4e4d5717d4dfc73e8

Later, when you review the pull request, you may consider adding this commit to your main repository.

spark2k06 avatar Feb 12 '23 16:02 spark2k06

Added Game Blaster (CMS) to Bitstream 3, now together with Adlib:

https://github.com/spark2k06/graphics-gremlin/commit/570dd635b6f7d3fd1c2424afc708305da7177bee https://github.com/spark2k06/graphics-gremlin/commit/60bb9b6b04fd7dfc5b2a54f15ddaacd58ec9269c

spark2k06 avatar Feb 16 '23 14:02 spark2k06

Improvement taken from the MiSTer PCXT port based on Graphics Gremlin, thanks to which some scenes from the Area5150 demo now look good:

https://github.com/spark2k06/graphics-gremlin/commit/42bff7bbfce0fb354c1455531b3c2b86d30055ae

image

Other graphical glitches were also not solved in the Graphics Gremlin part of the PCXT core, such as the initial text in the demo, with ghost lines appearing.

spark2k06 avatar Feb 17 '23 06:02 spark2k06

CGA and Hercules CRTC updated to UM6845R

https://github.com/spark2k06/graphics-gremlin/commit/8453503e26fb3384a3a737d101b5e054cf8a72e5

before:

image

after:

image

spark2k06 avatar Mar 12 '23 19:03 spark2k06

The latest commit https://github.com/spark2k06/graphics-gremlin/commit/8453503e26fb3384a3a737d101b5e054cf8a72e5 breaks CGA scan doubling.

  • @spark2k06 in his email mentioned that he intentionally disabled scan doubling because his VGA monitor works better with 15 kHz mode
  • In my tests with 3 different LCD monitors (spanning from early 2000 to a 2020 models) none of them were able to work with 15 kHz mode
  • I tried re-enabling scan doubling by reverting the relevant changes around cga.v lines 438-446 and all the cga_top.v changes. That somehow still didn't work
  • Finally, the scan doubling was re-enabled by reverting the https://github.com/spark2k06/graphics-gremlin/commit/8453503e26fb3384a3a737d101b5e054cf8a72e5 commit (the other change there seems to be moving to a different MC6845 implementation)

skiselev avatar Jul 20 '23 14:07 skiselev

The latest commit spark2k06@8453503 breaks CGA scan doubling.

* @spark2k06 in his email mentioned that he intentionally disabled scan doubling because his VGA monitor works better with 15 kHz mode

* In my tests with 3 different LCD monitors (spanning from early 2000 to a 2020 models) none of them were able to work with 15 kHz mode

* I tried re-enabling scan doubling by reverting the relevant changes around cga.v lines 438-446 and all the cga_top.v changes. That somehow still didn't work

* Finally, the scan doubling was re-enabled by reverting the [spark2k06@8453503](https://github.com/spark2k06/graphics-gremlin/commit/8453503e26fb3384a3a737d101b5e054cf8a72e5) commit (the other change there seems to be moving to a different MC6845 implementation)

On my old Nokia Display from 1999 this commit also don't work. I get black screen. But the improvement of CGA glitches in this commit are really cool. @spark2k06 Is it possible to add this improvements but disable 15 kHz mode ? At the moment you are the only one, who make active development on this project. It would be really a gift for the Retro PC community. Thanks

explit28 avatar Jun 18 '24 07:06 explit28