Neo Geo CPU Overclocking?

[FPGA64]

Has anybody attempted to modify the core to allow for multiple clock options and make it changeable on the fly via the OSD menu?

See https://github.com/MiSTer-devel/NeoGeo_MiSTer/pull/179

Changing the CPU clock as an option isn't very complicated, it's probably just that core devs rarely care much about features that didn't exist in original hardware.

From that Github thread (Your post)

Correct. I have modified a few of my MVS boards with overclock switches, feeding CPU from a different crystal. 18MHz is highest that is perfectly stable; 24MHz is unusable.

This is only helpful for Metal Slug games, others get graphics errors. It is especially useful for making Metal Slug 2 enjoyable, from worst to best game in series after overclocking.

So the option if added will result in many people complaining the core has corrupt graphics, simply beacause they dont understand the overclock option. This is why its a bad idea.

[Koston]

So the option if added will result in many people complaining the core has corrupt graphics, simply beacause they dont understand the overclock option. This is why its a bad idea.

So, a user would have a perfectly functioning core, set CPU overclocking, get corrupt graphics and blame the core?

Even pretending MiSTer users represent such rank stupidity, it still wouldn't differ from dozens of equivalent "unstable" options in other cores.

Not to mention NeoGeo software emulators, including MAME, which all also have overclocking option.

I really don't understand the NeoGeo templars' crusade against overclocking.

[FPGA64]

Yes thats exactly what would happen. People have the opinion that if an option such as overclock is present that it would work in every possible case. You can even mark options as dangerous as per the PSX core and people dont appear to realise that activating these is a Here be Dragons moment.

I can almost guarentee that someone will enter the help channels saying that the graphics are corrupt, and only after a long drawn out process say they have overclock turned on.

[dmckean]

That's how users learn though and eventually they'll stop messing with things they don't understand. We can't just dumb down the entire project and not implement features that would benefit nearly everyone because a few people won't understand it.

[prenetic]

So the option if added will result in many people complaining the core has corrupt graphics, simply beacause they dont understand the overclock option. This is why its a bad idea.

The PlayStation core handles this pretty gracefully, there are a set of advanced settings that you can change which clearly state they are unstable with a note in the OSD and an unstable designator "(U)".

[FPGA64]

So the option if added will result in many people complaining the core has corrupt graphics, simply beacause they dont understand the overclock option. This is why its a bad idea.

The PlayStation core handles this pretty gracefully, there are a set of advanced settings that you can change which clearly state they are unstable with a note in the OSD and an unstable designator "(U)".

And yet people routinely show up on Discord, complaining things dont work, swear blind they havent activated the options and then hours later admit they have them on and had forgotten

[Atohmdiy]

So the option if added will result in many people complaining the core has corrupt graphics, simply beacause they dont understand the overclock option. This is why its a bad idea.

The PlayStation core handles this pretty gracefully, there are a set of advanced settings that you can change which clearly state they are unstable with a note in the OSD and an unstable designator "(U)".

And yet people routinely show up on Discord, complaining things dont work, swear blind they havent activated the options and then hours later admit they have them on and had forgotten

You'll find anything don't you ?

[FPGA64]

The PlayStation core handles this pretty gracefully, there are a set of advanced settings that you can change which clearly state they are unstable with a note in the OSD and an unstable designator "(U)".

And yet people routinely show up on Discord, complaining things dont work, swear blind they havent activated the options and then hours later admit they have them on and had forgotten

You'll find anything don't you ?

An option that will lead to people wondering why the Core displays corrupt graphics, just so one game is changed from its original release is a poor choice. The only way to do this would be a OC core that could only play MS2

You may all think its not going to happen but past experience shows these sort of options lead to many complaints in Help Channels

[dmckean]

Other games benefit too and more choice is always better.

[Flandango]

I suggest somebody, just like that person who made the pull request adding the turbo feature, maintain an unofficial version with the added turbo feature.
It will never make it into Main because, as also noted in the actual pull request by the author, timing constraints are not met, which makes the WHOLE core, not just the TURBO feature, unstable. Unstable not just when Turbo is enabled, but entirely. It may not be evident at first or right away, but it's almost guaranteed somebody is going to find a pixel is off, a random crash, sound is off...whatever and complain.

[Nickie]

So the option if added will result in many people complaining the core has corrupt graphics, simply beacause they dont understand the overclock option. This is why its a bad idea.

what source/data/stats support that word that i've highlighted there?

OC option can be simply named "Unstable Overclocking (may corrupt graphics, use at own risk) : OFF (default) "

and people who complain can be mocked for their reading abilities

the OC option can even be in it's own sub-menu so a disclaimer against support requests can take the one line of text that would suffice

I can almost guarentee that someone will enter the help channels saying that the graphics are corrupt, and only after a long drawn out process say they have overclock turned on.

well if one person does that, then so be it, doesn't sound like the end of the world,
that said ,
instead of a long process, first question by those who know, on the help channel, shall be "first of all is Overclock on?"

before anything else, and then in those cases ( i don't think it will happen 10 times a week... ) troubleshooting simply ends there

[dshadoff]

Check the pull request. Sorgelig isn't going to accept anything that causes instability.

https://github.com/MiSTer-devel/NeoGeo_MiSTer/pull/179

[Nuclear3D]

Im just hoping someone will make a unofficial core when all is said and done with the 18 and 24hz overclock i get all the arguing back and forth about what's the point but for us that want it it worth it

[Atohmdiy]

I don't understand much this discussion in github. The neo geo core had two big update recently, one with the cd support and the other by Gyurco.
So when trbocode talk of the new version of the core, i assume it's the Gyurco changes, and that he will pull another request with higher clock speed (48M) ?

[dshadoff]

A "pull request" is actually a code submission in GitHub language.
There was a pull request made several months ago which would provide an overclocking option - but it was not accepted, as it appeared to increase instability (based on what I read of Sorgelig's comments).

Having said that, the Gyurco async clock fixes are intended specifically to stabilize certain aspects of the core, so Sorgelig may still look at a turbo option. Based on the frequency of updates, there could be more updates still coming.

Even if he doesn't implement turbo himself, he may now be more willing to accept one, as long as it is done in a way doesn't seem to destabilize (or conflict with the changes that are being implemented currently).

[Nickie]

Im just hoping someone will make a unofficial core

well there is one but it doesn't get updates

[Koston]

Check the pull request. Sorgelig isn't going to accept anything that causes instability.

https://github.com/MiSTer-devel/NeoGeo_MiSTer/pull/179

Quick recap for TL;DR people:

Overclocking a hardware NeoGeo system is only useful for playing Metal Slug games, fixing slowdown without adverse effects.

It breaks ALL other games, causing graphics corruption or worse.

So, why then? Because Metal Slug 2 Turbo on 18MHz overclocked PCB turns Metal Slug 2 from unplayable to the best game in the series. Gameplay video recorded from hardware:

[FPGA64]

It breaks ALL other games, causing graphics corruption or worse.

Also breaks the timing of the core making it unstable.So until that can be addressed the pull request will never make it through the system

[Koston]

It breaks ALL other games, causing graphics corruption or worse.

Also breaks the timing of the core making it unstable.So until that can be addressed the pull request will never make it through the system

That's fair, if the overclock option isn't working correctly, it shouldn't be merged.

I've used NeoGeo-18MHz-cpu-only_20220902 that didn't seem unstable to me, but admittedly haven't used it that much. As the name implies, this is what OC option should do - only change clock of the CPU, leaving all other timings untouched.

[Theenemy]

Is this the latest turbo hack available? (Sept 2022) Would be nice to have a new version so the neocd stuff could be overclocked as well

Hi.

Here is the 24MHz patched neo-geo core up to date.

[Lloyd2084]

If only someone could do the same for Shock Troopers 2.

I love that game but it was a bit too ambitious for the system. In 2p mode it can turn into a slide show.

[Atohmdiy]

It breaks ALL other games, causing graphics corruption or worse.

Also breaks the timing of the core making it unstable.So until that can be addressed the pull request will never make it through the system

You are the only one to find this is making the core "unstable". Maybe it does from a technical perspective, but from a player perspective, it is stable enough for a complete play-through of all metal slug games without any issue, major or minor... until recently.
I am using the 24Mhz version found in this topic, and play a lot to the metal slug games, sometimes in 2P, without issue. Recently the core start to crash, i think this version is too old now and is incompatible with the most recent mister main.

[FPGA64]

This is not at play time its at compile time. Until the compile can be done showing timing closure it wont make it to the mainline. If the compiler says its not making timing then by definition the core is unstable.

[Akuma]

People like what they like, there is no right or wrong answer when it comes to preferences.
You could always post a bounty for someone to fix it, maybe other people will chime in.

On a practical standpoint: why not use MGL's with the last core posted in this thread for the MSLUG games ?

[aberu]

What needs to be fixed about it? The core meets timing requirements when I compile trbocode's latest version.

I don't think doubling the clock is anywhere near the equivalent of what Koston's mods to his own boards are though. The current build is like clocking the board to 24MHz which is a bit excessive given 12MHz is the default.

The crashes you are experiencing @atohmdiy are not as much that the version is old, it's likely due to marginal timing. The SDRAM timing in this core is very touchy, we saw crashes before in older builds for a short time until sorg added some pipelining to smooth out some fairly hidden clock domain crossing.

[Akuma]

I never said anything about the core needing a fix. MSLUG2 clearly has a performance issue that people are trying to solve. So a 3rd party core, unstable or not is a good option to have.

I was reading up on it because I heard X was quite similar to 2. There was talk about hacking X to be like 2 here but I wonder if anything came of it or that it was wishful thinking.

[Atohmdiy]

What needs to be fixed about it? The core meets timing requirements when I compile trbocode's latest version.

I don't think doubling the clock is anywhere near the equivalent of what Koston's mods to his own boards are though. The current build is like clocking the board to 24MHz which is a bit excessive given 12MHz is the default.

The crashes you are experiencing @atohmdiy are not as much that the version is old, it's likely due to marginal timing. The SDRAM timing in this core is very touchy, we saw crashes before in older builds for a short time until sorg added some pipelining to smooth out some fairly hidden clock domain crossing.

What i do find strange is the fact it was working perfectly fine before, i played with this oc core to all metal slug games and never have any crash.
I mean, when you try to correct an issue, you need to isolate the problem. Here the OC core was working fine with the old mister main. After some update, the OC core was still the same and the main was updated, it's when the core start to crash.
I saw there was changes in the main framework to handle the new version of the core, including the cd addition and the "rewrite". So i assumed the old OC version crash for that reason.

[aberu]

I never said anything about the core needing a fix. MSLUG2 clearly has a performance issue that people are trying to solve. So a 3rd party core, unstable or not is a good option to have.

I was reading up on it because I heard X was quite similar to 2. There was talk about hacking X to be like 2 here but I wonder if anything came of it or that it was wishful thinking.

Things did come of it, this is just Metal Slug 2 Turbo, you can look up the hack. It isn't as much slowdown reduction as overclocking a real neo geo, but it's an improvement. It just removes code that makes it drop 2 frames instead of 1 frame, basically fixes a design flaw in the original game.

[Akuma]

Things did come of it, this is just Metal Slug 2 Turbo, you can look up the hack. It isn't as much slowdown reduction as overclocking a real neo geo, but it's an improvement. It just removes code that makes it drop 2 frames instead of 1 frame, basically fixes a design flaw in the original game.

I was under the impression that was a patched mslug2 not a mslugx patched to look like mslug2. But I'm no expert in this

Tried to locate a proper version of mslug2t but I'm having some trouble. Even got as far as manually building a .neo from the zip I found but I get graphical glitches so clearly I'm messing something up. (NeoBuilder just does not work on wine:arm64)

[Atohmdiy]

Get HTGDB game pack for the neo geo (try archive), mgs2 turbo is in the hack section.