Turbo Fix patch for Metal Gear 2

by sd_snatcher on 08-02-2009, 11:25
Topic: Development
Languages:

Konami's Metal Gear 2 is surely one of the highlights in MSX gaming. However, people often complain about the speed, which would be too slow when compared to Metal Gear 1. What happens is that the 3.5Mhz Z80A rarely can cope with the target frames-per-second the game was designed for. Probably the elevators are the only place during the game where the framerate is as it should be. But then there was another problem: if you try to run Metal Gear 2 on a 7Mhz MSX2 or turbo-R, the game runs too fast. This happens because its timing routine has a bug that allows it to run at 2x or even 3x the target framerate if the CPU can handle it.

sd_snatcher, from Brazil, has created a patch to fix this bug. Now it is possible to enjoy Metal Gear 2 in its full glory on a 7Mhz MSX2 or turbo-R, you'll have the same framerate as Metal Gear 1. The patch is available in both IPS and XPC formats.

Relevant link: FRS' MSX Page

Comments (23)

By Huey

Prophet (2642)

Huey's picture

08-02-2009, 11:29

Cool! For sure are going to try this!!!

Thanks

By ant0niutti

Master (159)

ant0niutti's picture

08-02-2009, 11:41

Good work!

Congratulations FRS.

By Randam

Paladin (874)

Randam's picture

08-02-2009, 12:42

Great patch!!! Works like a charm. Not as fast as booting the game with SHIFT key pressed though. But that's a fortunate thing: then the game becomes unplayable. And of course you can't save to disk anymore with the SHIFT trick.

Do you intend to make more turbo fixes since there are more games which have the same 'bug'? Hope so...

By sd_snatcher

Prophet (2839)

sd_snatcher's picture

08-02-2009, 21:07

Not as fast as booting the game with SHIFT key pressed though. But that's a fortunate thing: then the game becomes unplayable.

Well, but that's exactly what's this patch is all about: to let the game run with turbo at the correct (and playable) speed. Smile

And of course you can't save to disk anymore with the SHIFT trick.

"Trick" is the most appropriate word to define the use of the SHIFT key to enable the turbo. You know, that's not part of the game, but instead the Turbo-R diskROM is enabling the turbo. What happens when you press SHIFT on the boot of a Turbo-R without a cartridge? It goes to BASIC without drives and with the turbo enabled. As MG2 waits for the diskrom to boot so it can use it for savegames, the SHIFT key will enable the turbo before MG2 start running. But sadly, the speed bug was there up to now. This "press SHIFT to enable the turbo" will work with any cartridge (Konami or not) that waits for the diskrom to use it. Just try it on Kings Valley-2 or GameMaster 1/2 to see.

Do you intend to make more turbo fixes since there are more games which have the same 'bug'? Hope so...

Well, I do INTEND to do it. But this doesn't mean I'll have enough free time to really turn this a reality. Smile

By Randam

Paladin (874)

Randam's picture

08-02-2009, 22:43

Great to hear you intend to make more Turbo fixes LOL! Hopefully you'll have some spare time somewhere in the future. There are too few programs/ games that utilise the turbo R speed. So these are welcome additions. Hurrah!

And about the SHIFT trick: I noticed back in the nineties that it behaved that way. Don't know why I even tried that back then. After that tried it with other 'disk save/load' konami games. Particularly Shalom I found much better to play that way. Only boss 2 was real hard to beat with turbo enabled. Till this day I never thought it to be more than a konami feature/glitch. Thanks for the tip about it working on other games as well.

By Moniz

Champion (340)

Moniz's picture

27-03-2009, 01:48

I've tried to use the pathed rom with my mega scc flach card, but OPF seems to hang when before its flashing the card.
Is there a way to play the game using the scc flash card ?
I've pathed the to english translated version that works fine without the patch.

By sd_snatcher

Prophet (2839)

sd_snatcher's picture

07-04-2009, 00:04

I've tried to use the pathed rom with my mega scc flach card, but OPF seems to hang when before its flashing the card.
Is there a way to play the game using the scc flash card ?
I've pathed the to english translated version that works fine without the patch.

Weird. It should have worked properly. I'm sorry I don't have a scc flash card to test it.

By Manuel

Ascended (14683)

Manuel's picture

07-04-2009, 11:37

You can try it in openMSX, FRS... it's emulated.

By hama33

Supporter (1)

hama33's picture

15-04-2009, 16:44

Hey, im new here (and a complete noob to the MSX system!)

I applied the patch to the Metal Gear 2 rom using an ips patcher (dont quite remember the name, maybe ipswin..). Anyway, im using blueMSX and when i play the patched rom on the default 'C-BIOS' machine there is no change in speed (still slow). So i change the machine in the 'Emulation' settings to a Panasonic turboR (because turboR was mentioned in the post!) and the gameplay is at a much better pace, which seems like the right speed, however the frames per second drop to around 15 during gameplay. When i played the unpatched rom i got the original slow gameplay with fps of around 27!
So im just wondering what settings i should use on blueMSX to be able to play Metal Gear 2 with this patch at the correct FPS. Can anyone help??

Thanks alot!! Smile

By sd_snatcher

Prophet (2839)

sd_snatcher's picture

18-04-2009, 04:18

o im just wondering what settings i should use on blueMSX to be able to play Metal Gear 2 with this patch at the correct FPS. Can anyone help??

Sorry, I don't know too much about blueMSX's specific settings, but it shouldn't behave this way, at least on a fast PC. Have you tried the openMSX emulator on your PC?

By Muyfa666

Supporter (8)

Muyfa666's picture

22-11-2011, 08:25

Sorry to wake this topic up, but I wonder how I am supposed to use this? After patching the game speed shows no difference. Am I supposed to set my msx emulation to something special?

By Manuel

Ascended (14683)

Manuel's picture

22-11-2011, 21:19

No, because it works on real machines Smile It's just smoother and faster (especially the loading parts) on a turboR. Try that.

By Muyfa666

Supporter (8)

Muyfa666's picture

22-11-2011, 23:34

If I set machine to TurboR the game runs much better, but most things also runs a bit too fast. On regular MSX2+ I see no difference at all.

By Manuel

Ascended (14683)

Manuel's picture

23-11-2011, 20:10

Because it's a turboFix... it makes use of turbo. If your machine has no turbo, you will not really notice much.

By japanretroCT

Expert (106)

japanretroCT's picture

25-05-2014, 18:40

I have a panasonic msx2+ the fix will run game at 6mhz?

By sd_snatcher

Prophet (2839)

sd_snatcher's picture

25-05-2014, 19:23

It supports any turbo machine, but will only enable the turbo on machines that have the CHGCPU function on its BIOS. Currently, only the Turbo-R machines have that.

But users of other turbo machines can enable the turbo before running the game and it will work just fine.

But in Panasonic MSX2+ machines there's a caveat. The PSG and SCC will get out of pitch. The PSG gets out of pitch because of a design flaw in this computer's chipset. And the SCC will get out of tune because Konami saved some pennies and didn't include a crystal inside the cartridge.

You can fix the SCC issue using a Supersoniqs slot expander. This nifty expander has a built-in crystal to fix the pitch in cartridges that have this problem.

But to fix the PSG pitch would require the Panasonic MSX2+ to be modded.

I'm not sure if the latest version of the MegaFlashROM SCC+SD includes a crystal. Since this wonderful cartridge also includes a PSG, if it has a crystal that could be the easiest way to fix the PSG&SCC pitch issue of the turbo mode in Panasonic MSX2+ machines.

By japanretroCT

Expert (106)

japanretroCT's picture

27-05-2014, 20:24

Thankyou very much.....There is a schematic to mod panasonic msx2+ with a psg oscillator circuit?

By sd_snatcher

Prophet (2839)

sd_snatcher's picture

29-05-2014, 01:19

I don't know any ready schematics, but the solution is simple: Add a mini-PSG (YMZ284 or YMZ294) inside the Panasonic MSX2+, and use it to replace the sound output of the T9769 built-in PSG. The clock signal for the mini-PSG can be obtained from the YM2413 clock pin.

The built-in PSG will then only be used for the joystick ports. Both PSGs can work in parallel without trouble, because the mini-PSG is write-only.

You can also use the opportunity to upgrade the turbo to 7MHz, that is easy to do in this machine and will give it a nice speed boost.

If I had one Panasonic MSX2+, I would already developed such upgrades for it. Curiously enough, I know the Sanyo MSX2+ machines accept the very same upgrades.

By tvalenca

Paladin (704)

tvalenca's picture

29-05-2014, 20:37

The Panasonic MSX2+ (and Turbo-R ST) audio outputs are quite noisy... Instead of messing the internals of these machines, I rather building a PSG cartridge!

By sd_snatcher

Prophet (2839)

sd_snatcher's picture

29-05-2014, 21:25

I almost forgot! Padial has a nifty sound card with a built in crystal that can
Fix the sound pitch issue on Z80 turbo machines.

Check this link for the LPE San3:
http://msx.deneb.nl/pages.HTM

By Bersh

Supporter (1)

Bersh's picture

12-08-2015, 08:56

Thanks! I really appreciate this

By Grauw

Enlighted (7411)

Grauw's picture

09-08-2018, 15:05

Afaik the Panasonic in turbo mode only drives the PSG at 5.37 MHz and affects its pitch, while the bus clock speed is still 3.58 MHz as it’s supposed to, so other sound expansions (including the built in FM) sound with the correct pitch?

Would be nice if this turbo fix enabled the Panasonic MSX2+’s turbo as well, and adjusted the PSG frequencies by a factor of 1.5 to correct the pitch.

By Meits

Scribe (5116)

Meits's picture

09-08-2018, 18:00

External sound cartridges stay on the right pitch indeed. Though they will often miss (part of) a note. Just like a 7MHz adjusted FM-PAC or Music Module. It's just not ideal.

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