Genesis / Megadrive core ported to MiST

[Newsdee]

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!

[phoboz]

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?

[Sorgelig]

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?

what game you want to see?

[phoboz]

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?

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

[Sorgelig]

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.

[Gehstock]

Good Work, with Standart Mist Menu looks nice(ZPU have a Bug (lists not all Files on SDCARD))

[Sorgelig]

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

[Newsdee]

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!

[Sorgelig]

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.

[Sorgelig]

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.

[phoboz]

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?

[Sorgelig]

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.

[vebxenon]

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

[phoboz]

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.

[vebxenon]

Thanks very much for the answer Phoboz

[NML32]

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

[Sheldon]

Hello,
Anys news ??

[DrOG]

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

http://atari-forum.com/viewtopic.php?f= ... 90#p322190

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

[Gryzor]

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? ).

Also: salivating about MiSTer now

[Torlus]

Hi,
I am the original author of the fpgagen core (as well as some others, check https://github.com/Torlus/fpgapce and https://github.com/Torlus/JagNetlists
I've read that forum thread quickly, and it seems that getting a stable build is still an issue.
From what I've seen, no design constraints (.sdc files) have been written yet.
When I wrote that core in 2010, the Quartus version I was using used the "Classic Timing Analyzer".
However, IIRC, starting at version 13.0 of Quartus, there have been a switch to TimeQuest Timing Analyzer, and now synthesis relies heavily on how you constrain your design. It may appear as a burden at first sight, but I found it to be incredibly useful, once you get used to it.
If someone is interested to work on this subject, please let me know.
Regards,
Gregory

[Gehstock]

Thank you for your fantastic Work.

[Newsdee]

Thanks for these and the PC Engine core! I think the MiSTer port is a little more stable, due to having more FPGA space, but of there is a way to fix it on the MiST that would be great.

[DrOG]

I agree!

Awesome work , but MiST port is still not perfect...

[vebxenon]

I know the compatibility issues, but the main problem I see in the total unstability once you have load a rom and want to change the game. Most time I need to change the rom, MiST and core must be restarted. Will this problem be solved or OSD changed to the standard MiST OSD?

Regards,

Salva

[vebxenon]

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.

Any news about this porting?