Genesis Core

[Sorgelig]

What's the benefit of turbo on console? All games are written for standard speed.

[slingshot]

Tried mostly 3D games, and turbo CPU clock helps them. Look at Race Drivin' for example, or F117 Night Storm.

[Grego2d]

Sonic 1/2/3, splatter house 2 are prime examples.

[Grego2d]

Sorgelig, it makes spinball road rash and other games with slowdown/framerate issues run without slowdown.

Same as the superfx overclock or the Gradius III sa1 hack.

[Grego2d]

Also slingshot, if you look at my first attempt I'm just changing the rate of the clock, that version gives audio issues as well, so you might want to test on mister, this might only be an issue in the mister implementation.

[slingshot]

Also slingshot, if you look at my first attempt I'm just changing the rate of the clock, that version gives audio issues as well, so you might want to test on mister, this might only be an issue in the mister implementation.

I cannot do it, because I don't have one. I've checked Sonic1 on MiST, didn't notice anything unusual with CPU Turbo ON.

[Sorgelig]

I never noticed slowdowns on Sonic 1/2

[Grego2d]

Sorgelig, the only slow down in those games is when you lose a lot of rings. That's not what he's testing tho, overclocking causes audio issues in those games on mister.

[Grego2d]

Thank you for testing slingshot, how recent is your build of Genesis for mist? From the look of your code quite a bit is different.

[Grego2d]

I guess it would be prudent at this point to add an osd overclock option so I can see if audio problems clear up when disabled.

[Sorgelig]

Couple of attempts and I think I have Z80 communication fixed. Audio is still messed up in most games, but it's improved. I think the remaining issues are caused by the 68k accessing the psg directly, but I'm not sure.

What kind of audio issues you have? which games?

[Grego2d]

Wrong pitch/garbled sounds, sonic 1 2 and 3, splatterhouse 2, gunstar heroes, most games are having issues.

[Grego2d]

Just noticed sound debug option in Genesis.sv, recompiling with that so I can test FM/PSG individually.

[Grego2d]

Well, after testing it's both the FM and PSG having issues, hmmmm

In both cases some sounds are fine and others are messed up, Sonic 2 the jump sound is fine, other psg music sounds are wrong.

[Grego2d]

Added an osd option for turbo, turning off turbo after loading a game does fix the audio issues. Sorgelig, does the 68k access the FM chip directly as well as the PSG?

[Grego2d]

More testing, now that I can control turbo from the osd I can see the psg is actually working correctly. Only FM sounds are a problem.

Interestingly, sonic spinball only uses the FM chip and it sounds fine besides being higher pitched.

And apparently road rash is similiar, fm only, audio plays back at higher rate when overclocked resulting in higher pitch.

Gonna try a new tactic, only accelerate ram/rom reads/writes.

[slingshot]

More testing, now that I can control turbo from the osd I can see the psg is actually working correctly. Only FM sounds are a problem.

Interestingly, sonic spinball only uses the FM chip and it sounds fine besides being higher pitched.

And apparently road rash is similiar, fm only, audio plays back at higher rate when overclocked resulting in higher pitch.

Gonna try a new tactic, only accelerate ram/rom reads/writes.

The FM chip gets the same clock enable on MiSTer, as the CPU PHI1 phase, and it is also doubled then. Don't double the FM clock, and it'll be good.

[Grego2d]

Oh damn, I had not noticed that

Made the change, compiling. Thanks so much for your help slingshot

[Grego2d]

Assuming this works I'll clean up the code and send a pull request to Sorgelig shortly.

[Grego2d]

Works perfectly, this is awesome, code cleanup and pull request incoming.

Here's a working build in the mean time:

https://ufile.io/2h7up0ic

Did some more testing, it's the small things that are surprisingly impressive. Quicker load times on menus, toe jam and Earl goes to map twice as fast. Less lag in tight situations, splatter house 2 turn around ghosts cause no lag at all. Quite an improvement. So far the only game I've found to have an issue is earthworm Jim, slight hiccups in the audio.

Sorgelig, points at which Sonic 2 lags:
Losing too many rings
Tubes on chemical plant zone
Water rising on chemical pz
Bonus stages

[Grego2d]

I would have sent a pull request by now Sorgelig, however I did some minor refactoring and now Quartus won't produce a usable binary. I even reverted all my changes back to the working code and it produces cores that do nothing. Kind of at a loss here, just nuked my db/output_files/incremental_db folders, well see if that helps.

[Sorgelig]

Let me implement the Turbo by myself.
I know the core, so will do it.
It's just the feature i didn't think before. But not hard to implement.
Real turbo needs to include other tweaks. For example disable vdp fifo.

[Grego2d]

Sure, go ahead, was just trying to learn/help.

Btw did you try the build I posted on any of the games that have slowdown?

And out of curiosity, why would you need to disable the vdp fifo?

[Sorgelig]

I didn't express correctly. I mean disable fifo throttling.
I didn't try your build yet.

[Grego2d]

Ok, figured out the issue finally. Jesus, if you can't find a var Quartus throw a error not a warning...

Gonna send you a pull request when it's working anyway Sorgelig. If you use some of it cool, if not, no worries.