Genesis / Megadrive core ported to MiST

[Kujako]

This core uses *.bin-files only as format for rom images. Plus try PageUp & PageDown to navigate faster through list.
SBWin converts between popular formats of Megadrive rom images.

The problem is that for many of my ROMs, a blank line is shown instead of the name and everything after the first dozen or so are missing. As I said, same issue I see with the PCE core, looks like it uses the same or similar file manager. Not found a cause or solution as of yet...

So for example, while I have all the Sonics, I can only see and load the compilation ROM, which in this case is fine since that covers 1-3 and it runs quite well. But it loads slow, since its so large. I would rather just be able to load Sonic 1 if that's what I want to play.

Maybe it's time to sort out your roms Anyway check again if all of them are *.bin and *.pce only types of roms. Update to latest firmware, check|reformat file system of your memory card (fat16<->fat32 variants). In both cases with latest versions of PCE or Megadrive core, I didn't deal with problem of blanks spaces in file manager. I have own collection of best & selected games for both platfroms about 300+ something games and everything is going fine in terms of file manager of both cores.

Yup, did all of that many times. No idea what the underlying issue is.

[seastalker]

I revisited this Genesis core after many months away from it. WOW! What an amazing amount of progress! Thank you!! I've been playing emulators for a long time and some original hardware for the systems I have. THIS core really made me nostalgic by the FEEL of the no lag controls.

I think I read the sound in part or full was pulled from the SMS core. Since the Genesis/Mega Drive can play Sega Master System games through the power base converter peripheral, what are the technical aspects to [subjectively] the 'best' way to implement better SMS support on the MIst:

1. Rework the current SMS core.
2. Write a new one from scratch based off a SMS
3. Tweak the current Genesis core to include power base converter support

It's just hopes and wishes, but I think this subquestion is interesting and hope others do too.

Also, with the Genesis core, what is the "Sega Genesis_Megadrive.sof" file for? I looked up that .sof is sort of an SRAM but is this file for developers or are all MIst users of the core required to put it in the SD root?

[MasterOfGizmo]

I just added a new release. The CPU core has been updated from the very old tg68 to the latest tg68k as used in the amiga and atari st cores. I actually don't see a difference but it may be useful to check the newer version in case of problems with the old one. Also the overall cpu speeds may differ which may make a difference in some games.

The other change is support for the YPrPr cable (https://github.com/mist-devel/mist-boar ... PbPr_Cable).

[DanyPPC]

Tested new Genesis Core, it works very well. I think compatibility is the same as old core.
Used VGA only output, i have to contact one of my technician to realize the YPbPr cable for MiST.
Thanks

[desUBIKado]

With RGB mode the image is not centered and lost upper area

M800_fpgagen_RGB_out.jpg

With VGA mode the image is more or less centered

M800_fpgagen_VGA_out.jpg

This problem was already on old core.

Thanks a lot for this superb core.

[DrOG]

I just added a new release. The CPU core has been updated from the very old tg68 to the latest tg68k as used in the amiga and atari st cores. I actually don't see a difference but it may be useful to check the newer version in case of problems with the old one. Also the overall cpu speeds may differ which may make a difference in some games. The other change is support for the YPrPr cable.

Thank you for your effort!

Tried it only briefly, Worms has the same graphic glitches at the bottom of the screen as the previous release.

[MasterOfGizmo]

Worms has the same graphic glitches at the bottom of the screen as the previous release.

Do we have a screenshot of that? Is it just ~16 additional more or less random lines which shouldn't be there at all? Then it's the same issue i see on Sonic as well. This is probably a bug in the VDP implementation and for some reason it's just displaying too many lines in this case.

[MasterOfGizmo]

With RGB mode the image is not centered and lost upper area

Huh? Both screenshots say "TV - 15khz"

[desUBIKado]

Yes, I have a Mistica FPGA16 and I connect VGA and RGB/SCART to my monitor LG FLATRON M1917A at the same time. Then I switch the source of the image with TV remote control.

[MasterOfGizmo]

Yes, I have a Mistica FPGA16

Then you should get in touch with the makers of that board. I've never seen one myself and cannot help you there. I don't even know how their video works.

[desUBIKado]

Yes, I have a Mistica FPGA16

Then you should get in touch with the makers of that board. I've never seen one myself and cannot help you there. I don't even know how their video works.

OK. I understand the original MiST don't have this problem with RGB output on fpgagen core. I always use the RGB output with others cores without that issue. Thanks for your answer.

[DrOG]

Worms has the same graphic glitches at the bottom of the screen as the previous release.

Do we have a screenshot of that? Is it just ~16 additional more or less random lines which shouldn't be there at all? Then it's the same issue i see on Sonic as well. This is probably a bug in the VDP implementation and for some reason it's just displaying too many lines in this case.

Hi!

It looks like this (the screenshot is taken from the previous release of fpgagen core, but using the new one it looks the same):

[MasterOfGizmo]

That looks like the same issue i see with the Sonic intro. There a just too many lines displayed on the screen and the image should end ealier.

[vebxenon]

I just added a new release. The CPU core has been updated from the very old tg68 to the latest tg68k as used in the amiga and atari st cores. I actually don't see a difference but it may be useful to check the newer version in case of problems with the old one. Also the overall cpu speeds may differ which may make a difference in some games.

The other change is support for the YPrPr cable (https://github.com/mist-devel/mist-boar ... PbPr_Cable).

Thanks very much! Do you know if it's possible to change the OSD to the standard one? Now it's unstable.

[slingshot]

It is very difficult to debug this hardware because of all the pipelining -which follows original design. So I am currently working on a different approach. I am making a small 16-bit RISC CPU that can do the FM synthesis on software so it will be easier to debug problems and it will take less FPGA space. The second part is important because I am trying to make it fix on the ZX-UNO project too. I am rather advanced on this effort, which the assembler code of the synthesizer core ready and the Verilog implementation of the main units of the CPU done. But I still need more time to finish it.

Hi!

Just started to compile this core, and realized that the FPGA is almost full (and the compile time is huge) - JT12 eats lots of LEs, probably because many data are not inferred in BRAM. I don't know if this is by design, or by accident, would be good if it can be fixed.

[jotego]

This is mainly a reply to slingshot. Somehow I got an email from you but it didn't include the reply addess. It was sent through this forum, though.

The latest version of JT12 had FIR filters to improve sound on the FPGA 1-bit DAC. They take a lot of real estate in terms of LE. It also has a mixer to mix in the PSG sound in Megadrive. These two things are not an essential part of YM2612 and could be removed.

One problem JT12 has is clock synchronizers. Because the synthesizer uses a different clock rate from the rest of the system -as the real one does- that creates different clock domains and the way I sorted that out creates problems with some games as some music commands from the CPU seem to get lost. That is what happened with The Punisher, anyway. This is fixed in MiSTer using a simple yet smart hack from Alexey. The solution there is not totatlly portable to any system using a Yamaha synthesizer and an arbitrary CPU but for the specific case of Megadrive, it works well.

During the summer months I've been busy with travelling, reading and flamenco... so I didn't spend much time on this. Please use the MiSTer version for now as it is the most compatible one. The changes with JT12 v0.2 are minimum and for Megadrive work well.

[slingshot]

During the summer months I've been busy with travelling, reading and flamenco... so I didn't spend much time on this. Please use the MiSTer version for now as it is the most compatible one. The changes with JT12 v0.2 are minimum and for Megadrive work well.

Thanks for the answer! Strange the forum's message service didn't include the reply address.
I've already integrated the version you mentioned, and did some other rework on the core (e.g. use the standard MiST OSD and ROM loader, but in a compatible way with the other boards), the result is the FGPA's 27% is free now, so VDP development can continue, if someone is interested in it.

[DanyPPC]

Good news, thanks.

[MasterOfGizmo]

For a test i just disabled a feature called "v30 "in the core. At least in the Sonic intro this suppressed the additional lines at the screens bottom. Perhaps you'd like to check if this is also the case with the other games exhibiting this issue.

fpgagen.rbf.zip

The problem is that this is a feature of the genuine genesis vdp. So the question is why this is being triggered in the mist when it shouldn't ....

Edit: BTW, slingshot, the core name should imho be genesis instead of genesys
Edit²: Because V30 is in a a register _named_ mode register 2 but which actually is register 1

[slingshot]

It fixed AfterBurner and Dune II, too.

You're right about the core name, I think I was too tired to look out for the correct spelling I see also the auto-reset after the ROM loading is not quite stable yet, but resetting manually, then loading a ROM should help.

[MasterOfGizmo]

The correct fix is to change line 665 in vdp.vhd from

Code: Select all

  V30 <= REG(2)(3);

to

Code: Select all

  V30 <= REG(1)(3);

[Sorgelig]

The correct fix is to change line 665 in vdp.vhd from

Code: Select all

  V30 <= REG(2)(3);

to

Code: Select all

  V30 <= REG(1)(3);

after previous V30 mention i went to wiki to read about it and had weird feeling why it's REG(2)(3) in the code while should be REG(1)(3), but thought it may be counted from 1.

[slingshot]

Would be good if the other visual glitches could be fixed with other one-liners, like Double Dragon II, Outrun

[DrOG]

For a test i just disabled a feature called "v30 "in the core. At least in the Sonic intro this suppressed the additional lines at the screens bottom. Perhaps you'd like to check if this is also the case with the other games exhibiting this issue.

fpgagen.rbf.zip

The problem is that this is a feature of the genuine genesis vdp. So the question is why this is being triggered in the mist when it shouldn't ....

Edit: BTW, slingshot, the core name should imho be genesis instead of genesys
Edit²: Because V30 is in a a register _named_ mode register 2 but which actually is register 1

Hi!

Just tried this release, Worms shows the same graphic glitch at the bottom of the screen as the previous releases. Menu is standard and YUV out is flawless.

Thanks for your effort!

[MasterOfGizmo]

Worms looks like the displayed area of memory is incorrect. There's something missing at the top and garbage at the bottom.

But can only find a pal version which doesn't run at all in the fpgagen. So I cannot test myself.