NEO-GEO CPU overclocking?

[rgn]

Some really good NEO-GEO games (like Metal Slug or Shock Troopers series) are suffering from slowdowns... Is it possible to overclock the NEO-GEO core to make 68000 CPU 2x faster like some MAME emulators can do? How much work is required to do that? Something like Turbo mode of SNES core

[KremlingKuthroat19]

Great question! Metal Slug 2 is an outstanding game and even while playing the optimized hack of Metal Slug 2 Turbo, the game still has significant slowdown. I can't help you when it comes to the feasibility of a Turbo CPU mode for the NeoGeo core, but I certainly second your motion! If possible, a Turbo mode on the NeoGeo core would be a gamechanger.

[Coffea]

A turbo mode if possible would be a very welcome addition.

[Alkadian]

A turbo mode would be awesome indeed!

[Cyril1980]

Hi there,

Here is a modified NeoGeo_MiSTer core updated so that most components have a double clock speed ( MC68000 will run at 24MHz ).

This nearly eliminates all slow downs in Metal Slug 2 .

This is a quick and dirty hack while waiting for a better implementation from one of our expert FPGA developers.

I have attached the .rbf file as well as the modified source code ( .patch file ) if anyone is interested in checking the modifications I have done.
The source code has been forked from the official github at release 20200928.

Be aware that this core does only work on a handful of games, for the same reason an overclocked MVS hardware would: the LSPC ( GPU ) is not overclocked to keep the video synchronization and that may result in video glitches depending on how the game was programmed at the first place.

So please install this .rbf file alongside the official one and use it only on specific games.

[Alkadian]

@Cyril1980
That's awesome, many thanks for that! I can't wait to check it out!

[Cyril1980]

A different patch, this time with only the CPU overclocked to 24MHz.

It seems to remove some subtle visual glitches in Metal Slug 2. Not sure if this affects the performance negatively compared to the previous patch (which overclocks more components).

[lroby74]

Just a question, but on original Neogeo console Metal Slug 2 suffers of these slowdowns?

[rhester72]

@lroby74 very much so

[Cyril1980]

Just a question, but on original Neogeo console Metal Slug 2 suffers of these slowdowns?

Hi. Yes, Metal Slug 2 is well known for its terrible slowdowns (some people like them though). Multiple other games are impacted as well, like Storm Troopers 2 for example.

Take a look at the following video, shot from real hardware: https://youtu.be/VY9oFmTF_PM.

[lroby74]

Take a look at the following video, shot from real hardware: https://youtu.be/VY9oFmTF_PM.

I've just seen video.. it's very visible!

[zakk4223]

There's a metal slug 2 turbo patch floating about on the internet: some of the problem is an error in the game's code that can be fixed.
I believe it is in mame as mslug2t.
I'm not sure if it is in the various darksoft packs
Edit: It's in the mister romset.xml as 'Metal Slug 2 (Turbo Hack)'

[Cyril1980]

There's a metal slug 2 turbo patch floating about on the internet: some of the problem is an error in the game's code that can be fixed.
I believe it is in mame as mslug2t.
I'm not sure if it is in the various darksoft packs
Edit: It's in the mister romset.xml as 'Metal Slug 2 (Turbo Hack)'

Partially fixed, sadly. There are still slowdowns with it...

[Aspie]

Thanks for this Cyril. Metal Slug mission 5 when there are loads of soldiers on screen trying to jump on your tank, this version certainly makes a difference with no slow down.

[KremlingKuthroat19]

Absolutely brilliant work. From what I can tell this doesn't seem to affect any other games negatively, meaning everything runs much smoother and optimized. Metal Slug 2 with this CPU overclock and using the Turbo ROM hack removes 90% of the slowdown. Essentially, the game is much more enjoyable now.

Is there a way you can add this to the main repo of the official core? This feature is a gamechanger and I just want everyone to be able to experience it with ease.

[Cyril1980]

Absolutely brilliant work. From what I can tell this doesn't seem to affect any other games negatively, meaning everything runs much smoother and optimized. Metal Slug 2 with this CPU overclock and using the Turbo ROM hack removes 90% of the slowdown. Essentially, the game is much more enjoyable now.

Is there a way you can add this to the main repo of the official core? This feature is a gamechanger and I just want everyone to be able to experience it with ease.

It is really a hack, it would not be great to include this in the current state into the main repo IMHO.
The best would probably be to track down the clock signals inside the LSPC and also overclock those that do not alter the video synchronization.
This would require a developer with very good understanding of the neogeo internals I suppose.
But thanks a lot for your super positive feedback!

[KremlingKuthroat19]

As you saw in my other thread about Windjammers, there are some issues that arise when using the CPU overclock hack.

However, Metal Slug 2 was such a better experience and is my favorite Neo Geo game so it'd be really cool to get this officially added to the core, but it'd need to be implemented correctly so that game compatibility isn't affected.

Are there any other games that have slowdown issues besides the Metal Slug series that any of you are aware of? Regardless, maybe Furtek or Jotego could look to see if this could be implemented as a side project. It'd be really cool and would be the cherry on top for this core as it's pretty amazing as is.

[Alkadian]

A different patch, this time with only the CPU overclocked to 24MHz.

It seems to remove some subtle visual glitches in Metal Slug 2. Not sure if this affects the performance negatively compared to the previous patch (which overclocks more components).

@Cyril1980,
I have finally managed to try your patch. It's fantastic! Many thanks for that. I have experienced no slow down at all with MSL2 which is one of my favourite games of all times! Well done!

[rgn]

@Cyril1980 I've tried you patch and it works awesome with Metal Slug games. Doesn't work for Shock Troopers tho, but it is not a big deal. Thank you so much!

[Atohmdiy]

Excellent indeed, also try it in metal slug 2 and it's so much better. Thank you !

[rgn]

Excellent indeed, also try it in metal slug 2 and it's so much better. Thank you !

yeah, I've just beaten this game. Gameplay totally changed, nice and smooth. Love it

[Jinxz]

To be honest I am completely lost here... I've been running emulators since 20 years and just a short while ago I moved to FPGA only because I've been surrounded by people in my community that moved beyond emulation and started using FPGA and convincing me of its pure way of playing the good old games. Not because it is easy but because the hard work setting it up leads to the 1:1 experience I once had.
I played Metal Slug when it came out on the Neo Geo back in the day and it had slowdowns...

Now 24 years later we moved passed emulation and we're on a forum because we want the 1:1 experience and there is talk about how shitty the slowdown in Metal Slug is? Didn't you play the game back in the day? If yes, and you still want to "turbo boost" so that you're not bothered with the 1:1 expierence, please buy an 5K pc with a 3090 and an 8K monitor and run an emulator.

My 2 cents

[Cyril1980]

To be honest I am completely lost here... I've been running emulators since 20 years and just a short while ago I moved to FPGA only because I've been surrounded by people in my community that moved beyond emulation and started using FPGA and convincing me of its pure way of playing the good old games. Not because it is easy but because the hard work setting it up leads to the 1:1 experience I once had.
I played Metal Slug when it came out on the Neo Geo back in the day and it had slowdowns...

Now 24 years later we moved passed emulation and we're on a forum because we want the 1:1 experience and there is talk about how shitty the slowdown in Metal Slug is? Didn't you play the game back in the day? If yes, and you still want to "turbo boost" so that you're not bothered with the 1:1 expierence, please buy an 5K pc with a 3090 and an 8K monitor and run an emulator.

My 2 cents

Hi.

We play on FPGA for different reasons.

My own reason is input lag. If emulators could emulate without adding multiple frames of input lag and destroy the original experience, I would certainly play on raspberry pi. But this is not the case as of today. And please do not come up with the retroarch hack to shave up frames of lag through fast forwarding, this is really not great. Ever tried that on Tetris for example? It’s awful.

That’s my 2 cents.

[KremlingKuthroat19]

Hi.

We play on FPGA for different reasons.

My own reason is input lag. If emulators could emulate without adding multiple frames of input lag and destroy the original experience, I would certainly play on raspberry pi. But this is not the case as of today. And please do not come up with the retroarch hack to shave up frames of lag through fast forwarding, this is really not great. Ever tried that on Tetris for example? It’s awful.

That’s my 2 cents.

That's exactly why I'm here too. Input lag and playing old games as close to authentically as possible on a modern TV under one platform.

Adding a turbo feature is simply an option. One that you can choose to use or choose not to use if you so please. It's always better to have options. If you want an authentic experience then you don't need to use a turbo feature, if it's ever added.

The GBA core has fast forward, rewind, and save state support. It also has a turbo feature, and a 2X resolution feature. Should we remove those options too because it's not authentic? No because they're options that you can ignore if you don't like them.

If the game's timings are off-kilter and running too fast then the turbo feature becomes a hindrance, but in the case of minimizing frame rate dips to give the game a reliable framerate, I think that a turbo feature is a great option.

I'm no expert on CPU clock speeds and whatnot, but if a turbo feature could focus on just keeping the framerate from dipping and minimize increasing timings in various games, then it'd be ideal.

[rgn]

To be honest I am completely lost here...

And you're still lost. You don't get the whole idea of FPGA. It is not about 1:1 experience, it is about 1:1 accuracy of hardware replication. You've been using emulators for 20 years? Are you sure you are the right person to talk about "1:1 experience"? 1:1 experience is about having an old console and an old TV.
Why don't you blame filters, turbo modes, extra sprites in other cores then?

I love MiSTer. We now have an accurate console replicas in one box with all the advantages of modern emulators, i.e. hdmi output, scanlines, turbo CPUs, extra sprites and cheat codes. If you don't like any of that - just don't use these features...