Genesis / Megadrive core ported to MiST

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Re: Genesis / Megadrive core ported to MiST

Postby seastalker » Wed Oct 31, 2018 11:49 am

DannyPPC - yes thank you on Shadow Dancer! That 3 button mode did the trick! The sound glitched midway through the game but not too bad. Haven't played in a while and made it to final boss on my first game with no continues... I nearly beat him, then I had to use all my continues. That's ok, I won years ago. :)

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Re: Genesis / Megadrive core ported to MiST

Postby jotego » Wed Oct 31, 2018 1:12 pm

DrOG wrote:
slingshot wrote:
DrOG wrote::cheers: Boldog szülinapot!

José nem biztos, hogy érti :D

I suppose Google Translate is his friend :wink:


Indeed! I had to use it. Thanks guys!

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Re: Genesis / Megadrive core ported to MiST

Postby MasterOfGizmo » Wed Oct 31, 2018 1:50 pm

I am still trying to get the Sega guys at sega-16.com interested. But they have an interesting forum. You need to earn points by posting before you are allowed to post anything ... anyone here already have a working account there?
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Re: Genesis / Megadrive core ported to MiST

Postby DanyPPC » Wed Oct 31, 2018 2:25 pm

That's interesting, but i have never attended / read that forum.
That's a pity.

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Re: Genesis / Megadrive core ported to MiST

Postby slingshot » Wed Oct 31, 2018 6:10 pm

MasterOfGizmo wrote:I am still trying to get the Sega guys at sega-16.com interested. But they have an interesting forum. You need to earn points by posting before you are allowed to post anything ... anyone here already have a working account there?

If working on an FPGA replica of the Mega Drive doesn't worth some points, then what? :)

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Re: Genesis / Megadrive core ported to MiST

Postby slingshot » Thu Nov 01, 2018 3:34 pm

Just uploaded a new release, with some bugfixes in the VDP. Also the sprite engine was re-structured greatly, to resembles what the hardware really do. Hope didn't introduce regressions. Also our emulator doesn't suxx anymore (if you know what does it mean).

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Re: Genesis / Megadrive core ported to MiST

Postby vebxenon » Thu Nov 01, 2018 3:43 pm

slingshot wrote:Just uploaded a new release, with some bugfixes in the VDP. Also the sprite engine was re-structured greatly, to resembles what the hardware really do. Hope didn't introduce regressions. Also our emulator doesn't suxx anymore (if you know what does it mean).


Thank you! :cheers: :cheers:
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Re: Genesis / Megadrive core ported to MiST

Postby DanyPPC » Thu Nov 01, 2018 5:02 pm

slingshot wrote:Also our emulator doesn't suxx anymore (if you know what does it mean).


You are right ! :)

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Re: Genesis / Megadrive core ported to MiST

Postby Televicious » Thu Nov 01, 2018 5:30 pm

MasterOfGizmo wrote:But you could use a megadrive->USB adapter with a megadrive pad and the MIST.


Sounds like the best option, hopefully it maps. Thanks for the suggestion.

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Re: Genesis / Megadrive core ported to MiST

Postby DanyPPC » Thu Nov 01, 2018 7:10 pm

Now the intro graphic in Super Skidmardks is correct. Good job guy !

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Re: Genesis / Megadrive core ported to MiST

Postby Estrayk » Thu Nov 01, 2018 7:16 pm

Higgy wrote:Nice work getting some of those undocumented features working!

There is an Emulator comparison video running the TiTAN - Overdrive 2 demo https://www.youtube.com/watch?v=_FyQPn89RZQ

I don't know if this helps at all? I thought that if an Emulator is running a particular part of the demo correctly, then maybe the emulator's Sourcecode could be looked at to see how a particular feature was implemented?


Overdrive demo works perfectly. About TITAN Overdrive 2 demo I think its a big a challenge because as you say, almost just ONE emulator can with it, anyway, it is a good start:

TITAN Overdrive 2 demo
MIST core fpgagen_20181101.rbf

https://www.youtube.com/watch?v=U1-E3xn6Ics

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Re: Genesis / Megadrive core ported to MiST

Postby slingshot » Thu Nov 01, 2018 8:12 pm

That's a great quality capture!
I know almost all reasons for the visual non-perfections, except the artifacts on the background of the rotating Overdrive logo (from 1:58 to 2:05).

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Re: Genesis / Megadrive core ported to MiST

Postby Estrayk » Thu Nov 01, 2018 9:32 pm

slingshot wrote:That's a great quality capture!
I know almost all reasons for the visual non-perfections, except the artifacts on the background of the rotating Overdrive logo (from 1:58 to 2:05).


Yep, I've a uncommon SVGA capture card. Great to listen that you know all reasons for future bug-fixed core versions but the music is also bugged. We've to talk with jotego. :D
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Re: Genesis / Megadrive core ported to MiST

Postby slingshot » Fri Nov 02, 2018 12:21 am

Here's a version which works better with Titan2 (textured cube and plasma columns are perfect), also the sound crashes less often at the opening scene. Just would be good to test for game compatibility, too (I prefer that instead of that one demo).
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Re: Genesis / Megadrive core ported to MiST

Postby DanyPPC » Fri Nov 02, 2018 8:18 am

Will it be possible to support interlaced screens ?

An excellent result has been achieved.

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Re: Genesis / Megadrive core ported to MiST

Postby slingshot » Fri Nov 02, 2018 8:46 am

DanyPPC wrote:Will it be possible to support interlaced screens ?

An excellent result has been achieved.


I'm thinking about it, but "excellent" means 2 games only in 2 players mode with flickering on VGA.

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Re: Genesis / Megadrive core ported to MiST

Postby MasterOfGizmo » Fri Nov 02, 2018 12:29 pm

That's the problem with interlaced modes. It's not really trivial to expand them to VGA. A simple scan doubler with a one line offset between both half images will result in flicker. For more complex flicker fixing we don't have sufficient internal FPGA memory.

On the other hand: Interlaced modes are designed to flicker. That's how they worked in the first place. And imho the MIST is supposed to give you the retro feeling back. For perfect video processing i'd suggest to use an emulator. That's why i am hesitating to add hq2x scaling.
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Re: Genesis / Megadrive core ported to MiST

Postby DanyPPC » Fri Nov 02, 2018 1:50 pm

I like the retro-feeling.

Minimig core support interlaced screen, and it is as close as possible to a real Amiga.
I have a boot picture interlaced on my installed Workbench 3.1 on MiST. :wink:

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Re: Genesis / Megadrive core ported to MiST

Postby MasterOfGizmo » Fri Nov 02, 2018 2:34 pm

As slingshot said: This is several hours of work for just two games ...
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Re: Genesis / Megadrive core ported to MiST

Postby DanyPPC » Fri Nov 02, 2018 4:49 pm

This is true.

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Re: Genesis / Megadrive core ported to MiST

Postby ijor » Fri Nov 02, 2018 8:31 pm

Hi,

MasterOfGizmo wrote:Ok, yes, the priority is an external thing but the CPU behaves differently depending on the level reported via IPL. My question was more or less: Are the IPL signals re-evaluated multiple times during one complete INT processing? E.g. there must be one point where the cpu detects that the IPL is != 7 and it thus has to take action. But there's also a moment where the decision which vector to use is done on base of the IPL. So when the IPL changes it may happen that some IPL that was applied at least one previous CPU cycle is ignored. That would rarely happen on the tg68k as it usually reacts immediately since most instructions require one cycle only. The IPL != 7 would always be handled at the end of the current instruction which in 99% of the cases means "now"...

That's sufficient. So there's one point where the ipl is evaluated.


I finally could check this.

Yes, IPL is evaluated and latched at the very same cycle. In other words, there is one cycle that the CPU takes the decision to take the interrupt, and at the same cycle it also latches and remembers the current value of the IPL signals. The state of the IPL signals before that cycle is not relevant, and any change after that cycle is ignored for the current interrupt process.

As said already, the exact cycle is variable and it depends on the microcode of the specific instruction being executed.
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Re: Genesis / Megadrive core ported to MiST

Postby Sorgelig » Fri Nov 02, 2018 9:56 pm

Generally Genesis games are not required cycle accurate CPU (except couple demos specifically requiring it). Just because many games have bugs and by different reasons these bugs are hidden/eliminated due to specific place/time the cycle accurate CPU is good to have in Genesis.

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Re: Genesis / Megadrive core ported to MiST

Postby jotego » Sat Nov 03, 2018 9:16 am

Major Release

After a week of hard work, I have completely re-written the phase and envelope generators. The purpose was to made them easier to simulate so I could catch bugs. I found many bugs, corrected them all. Now, all games tested sound good. So I have made a new release, version 0.5 named Dia de los muertos after the Mexican holiday happening this week.

The core volume is still relative low. I cannot increase another factor of 2 (+6dB) without clipping. When I tried, I noticed heavy distortion on Kuuga game over screen. PSG sound is too loud in comparison. It should be reduced at the system level on FPGAgen. I'll see if there are other options, but we may be stuck with this. Note that a sine wave (and FM is about sine waves) has much less power than a square wave (PSG) of the same amplitude and frequency. So it is normal that FM sounds quieter.

I still have to verify that a rarely used feature called CSM works well. That's the only pending task before closing this development. I don't know of any game that uses it.

Please report FM sound issues on the github project page. You can tell if it is an FM sound problem by disabling the PSG sound through the F12 menu.

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Re: Genesis / Megadrive core ported to MiST

Postby Higgy » Sat Nov 03, 2018 3:10 pm

Well done jotego on the continued development. Looking forward to seeing this integrated into the latest Core.

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Re: Genesis / Megadrive core ported to MiST

Postby slingshot » Sat Nov 03, 2018 4:14 pm

Outrun produces some extra percussion using the PSG. I don't feel it's too loud, but it's subjective of course.


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