Genesis / Megadrive core ported to MiST

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Re: Genesis / Megadrive core ported to MiST

Postby Newsdee » Wed Jun 21, 2017 6:55 am

I noticed this on the page:
MiSter allows to use USB storage for cores and their data


This might work with a Retrode, a cart dumper that presents itself as a USB storage to the PC. Then we could play Genesis games from carts! :)

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Re: Genesis / Megadrive core ported to MiST

Postby phoboz » Wed Jun 21, 2017 7:28 am

Sorgelig wrote:After i've replaced VRAM with BRAM, large sprite problem has gone!

That sounds impressive, could you post a video for those who does not have the MiSTer yet? :angel:

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Re: Genesis / Megadrive core ported to MiST

Postby Sorgelig » Wed Jun 21, 2017 10:21 am

phoboz wrote:
Sorgelig wrote:After i've replaced VRAM with BRAM, large sprite problem has gone!

That sounds impressive, could you post a video for those who does not have the MiSTer yet? :angel:

what game you want to see?

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Re: Genesis / Megadrive core ported to MiST

Postby phoboz » Wed Jun 21, 2017 11:35 am

Sorgelig wrote:
phoboz wrote:
Sorgelig wrote:After i've replaced VRAM with BRAM, large sprite problem has gone!

That sounds impressive, could you post a video for those who does not have the MiSTer yet? :angel:

what game you want to see?

For example Sonic The Hedgehog, since there are some other videos on the net of that game where the flickering is visible (most notably on the demo of the Marble Zone) That one will start after the title screen appears again after the first stage demo. Like in this video: https://m.youtube.com/watch?v=uaoyPK1pr40

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Re: Genesis / Megadrive core ported to MiST

Postby Sorgelig » Wed Jun 21, 2017 7:58 pm

I don't know why, but video sticks in processing stage on youtube.
There you will see MK3, Sonic the Hedgehog, Lemmings games. You can compare with MiST version.
Last edited by Sorgelig on Thu Jun 22, 2017 1:21 am, edited 1 time in total.

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Re: Genesis / Megadrive core ported to MiST

Postby Gehstock » Wed Jun 21, 2017 9:19 pm

Good Work, with Standart Mist Menu looks nice(ZPU have a Bug (lists not all Files on SDCARD))
Not only my Cores for Mist : https://github.com/Gehstock/Mist_Cores
My Cores for Mister : https://github.com/Gehstock/Mister

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Re: Genesis / Megadrive core ported to MiST

Postby Sorgelig » Thu Jun 22, 2017 12:19 am

video is finally uploaded on youtube: https://www.youtube.com/watch?v=6IuXCm3R5_M

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Re: Genesis / Megadrive core ported to MiST

Postby Newsdee » Thu Jun 22, 2017 12:23 am

Weird, Sonic is scrolling in the opposite direction? That's interesting... would make for a nice challenge :)
But it looks fantastic. All the flickering issues are gone!

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Re: Genesis / Megadrive core ported to MiST

Postby Sorgelig » Thu Jun 22, 2017 1:34 am

Notice ROM loading speed? Much faster than on MiST.

Also i've managed to re-make the core without using SDRAM at all. System RAM and Video RAM use FPGA block RAM. ROM uses DDR3 memory.

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Re: Genesis / Megadrive core ported to MiST

Postby Sorgelig » Thu Jun 22, 2017 1:55 am

Hmm.. music is weird after migrating ROM to DDR3. It seems Genesis is sensitive to RAM access time even for music. Well, going back to SDRAM.

I was wrong. There are no additional issues while using DDR3 for ROM. It's just core itself has meta-stability issues.
Actually this core has longest compile time among other cores. Even Minimig needs shorter time to compile.

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Re: Genesis / Megadrive core ported to MiST

Postby phoboz » Thu Jun 22, 2017 9:25 am

Yes the stability issue from build-to-build has been a problem for a while, but that now that you have got rid of the zpu and firmware at least some improvement must have been made. Also with a larger fpga routing should have a higher chance to succeed, but as I have learned setting up proper constraints should really be the key to a proper routing from build-to-build. Since many of us seem to have a software background (including myself) this is something new to learn. We did make a shortcut, to set routing option for low power optimization, which would shorten the signal path, but it also increases the routing processing time a little bit. Note that the Genesis is actually a quite complex system, having two different computers (68k and z80) communicating over a shared bus, dma etc. It is actally not that far from SEGAs system 16 arcade board, only with a weaker video display sub-system.

The core has been inherited from Torlus, so I am not aware of all features. I have started several attempts to clean it up, for example I wanted to lift out the scandoubler from the vdp and use the external scandoubler used by many MiST projects but failed. Maybe it has to do with the fact that a scanline is 3420/80 = 427,5 pixels clocks, and the scandoubler module can't handle that.

@Sorgelig, great progress with fixing the sprite flickering issue! I never realized that an fpga could have so much memory to fit the video ram for a 16-bit system. Strage with reverse Sonic, are you sure you are not using a hacked rom? What about other platformers, are they reversed too?

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Re: Genesis / Megadrive core ported to MiST

Postby Sorgelig » Thu Jun 22, 2017 1:54 pm

Don't mind about Sonic. I've just picked a random Sonic ROM. May be it's altered or special version - it's nothing to do with the core.

I think Audio part should be updated too. jotego's FM core has update since integration. PSG needs update. Audio volume is very very low.

About future video improvement without using BRAM: I think it's possible to fix the flickering - just SDRAM controller needs big change. It's too cluttered from my point of view. Probably it's possible to disable refresh cycle since video output already acts as refresh. Just need to check if screen size cover all rows.
Anyway, core needs more improvements. I'm not a big fan of Sega and i don't know every bit of its hardware, so i won't do much for the core.

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Re: Genesis / Megadrive core ported to MiST

Postby vebxenon » Sat Jun 24, 2017 11:36 am

And it's possible to put these changes on MIST or this will be only for other boards?

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Re: Genesis / Megadrive core ported to MiST

Postby phoboz » Sat Jun 24, 2017 2:25 pm

The MiSTer rom loader and OSD shall be possible to port back to MiST, thus much FPGA space will be saved. Regarding sprite flickering we need to find a way to imporove the SDRAM controller, as the MiST FPGA does not have enough block ram to use for video memory.

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Re: Genesis / Megadrive core ported to MiST

Postby vebxenon » Sat Jun 24, 2017 10:52 pm

:wink: Thanks very much for the answer Phoboz

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Re: Genesis / Megadrive core ported to MiST

Postby NML32 » Sat Jul 01, 2017 10:39 pm

Has anyone tried FixItFelixJr_AirwalkStudios.bin? I can't seem to get past the "Press Start" title screen.

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Re: Genesis / Megadrive core ported to MiST

Postby Sheldon » Wed Jul 12, 2017 8:44 pm

Hello,
Anys news ??

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Re: Genesis / Megadrive core ported to MiST

Postby DrOG » Fri Jul 14, 2017 4:49 am

Sorgelig made some progress during his MISTer project, but the core has still metastability issues:

viewtopic.php?f=101&t=31825&p=322190#p322190

I wonder if someone, who has the necessary knowledge is interested porting his work back to MIST?

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Re: Genesis / Megadrive core ported to MiST

Postby Gryzor » Fri Oct 20, 2017 7:23 am

This project had completely passed me by... I'm so glad it exists, even though progress has slowed. This could possibly make my MiST replace my SMD after the multicarts voltage brouhaha that took place a while back, instead of having to buy a Mega EverDrive X5 to replace my EverDrive MD (anyone has one to sell? :D ).

Also: salivating about MiSTer now :D
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