Messing around with debug modes

Golf
Technically this isn’t debug stuff, but I’ve been messing with Golf for the last couple of days. There’s two findings of particular interest.

Firstly, the Japanese ROM is capable of saving if you run it via emulation or on a flash cart with save support, because the game has a whole save system set up which relies on a check for functioning saveRAM on the cart. This removes the preset save slot 1 (T&ESOFT, called Duff in the US version) and password screens entirely. For cost-cutting reasons, when T&E Virtual Golf (the Japanese version) was released it did not have saveRAM on the board, so on official cartridges that check does its job and causes the game to fall back to the familiar password-save mechanism.

For the USA release, they went further: in addition to the physical saveRAM being MIA, the saveRAM check is hardcoded to fail, and once again the game drops back to the password system. However, it was only that check which was disabled in the US version; all of the other saving code has been sitting on the ROM unused for the last 29 years or so. Fortunately, it was possible to restore the saveRAM check by comparing against the Japanese version, and there’s now a patch available here on virtual-boy.com or at the Golf page on The Cutting Room Floor to restore saving in the USA version when played via emulators or flash carts with saveRAM support.

Secondly, there’s a newly discovered cheat in the game which disables the wind. Simply (or not that simply, it’s a little bit awkward) hold the following buttons while starting up the console:

• Select
• Left D-Pad Left
• Right D-Pad Right

If you’re playing on the stock game (e.g. official cartridges or an unpatched USA ROM), this will also change the default save slot name from Duff (US)/T&ESOFT (JP) to VICTORIA.WON. I don’t know who Victoria is or what they won, anybody have ideas? Is this some sort of golf joke that I’m too uncultured to understand? Anyway, if you’re playing on a version of (T&E Virtual) Golf which supports saving, you won’t see the VICTORIA.WON part, because as mentioned, default player names don’t exist when saving is enabled. However, the wind will still be disabled.

Thanks!

I have also seen your other patches for Red Alarm and Mario Clash.

Just to catch people up who aren’t on the Discord, after I restored the dummied saving feature in Golf, Super Bros. asked if it would be possible to get games to save even if they weren’t originally designed for saving, like Golf. I answered, perhaps a little optimistically, yes: you’d just have to redirect writes to memory to SRAM instead. In practice it’s been a bit more complicated than that, but you can see the results on my vb-patches GitHub repo, which currently has save patches for Golf, Jack Bros. (also doubles as a debug mode patch), Mario Clash and Red Alarm.

So in theorey this means you can create reporcards with sram saving features for those three games?

I can say with a high degree of confidence: maybe. If they work on flash carts, then they should also work on reproduction carts. That said, I really don’t even know that they work on flash carts currently. I don’t own a Virtual Boy myself, so all of this has only been tested via emulation in Mednafen and Red Viper. There shouldn’t really be anything dramatically different about running them on real hardware, but you never know.

There’s also at least some potential that I broke something in the process of creating these patches. I haven’t tested the games all the way through to make sure there’s no negative effects. For example, the initial release of the Golf save patch had a bug which caused it to overwrite a graphic on the in-game Depth settings screen. That was relatively harmless and it’s been fixed and updated since, but making a repro of any of these hacks would require a high level of faith in these relatively untested hacks.

In short, it should be possible to make repros of any one of these games with added SRAM support, but I’d personally warn against it until the hacks have been field-tested a bit more.

In the meantime, if you get a chance, would you mind testing a couple of button combos in Mario Clash to see if they make any difference?

First up, from basically anywhere in the game (title screen, intro, gameplay), press L + R + Select + Start + A + B. I know that’s a lot of buttons to press at once, sorry. This is the soft reset feature built into the game, so I’m just curious if a reboot would fix the graphical issues.

Secondly, I’d like you to try the SRAM reset button combo. From the title screen (and only the title screen, it won’t work anywhere else), press L + R + Left D-Pad Down + Right D-Pad Down. That should erase the SRAM and restart the game, similar to the soft reset. I’d be very interested to know if that fixes anything.

Thanks so much, I really appreciate your help.

Currently my running theory is that perhaps there’s less SRAM available than I’ve been assuming. I think the understanding is that there’s 64 KB available, although the Sacred Tech Scroll doesn’t really specify, it technically lists a range of 06000000-06FFFFFF which is like 2 GB, but I’ve been running with the theory that it behaves the same as work RAM, where the range is technically 05000000-05FFFFFF but the effective range is 05000000-0500FFFF (64 KB) and the rest is mirrors. Emulator saves are all 64 KB, so this seemed like a reasonable assumption, but emulators be emulatin’.

If the SRAM range is actually smaller than that, then something weird could be happening when I do my SRAM initialization, because I’m writing out the full 64 KB with zeroes before I start using it. If some of that range is inaccessible or mirrors for something else and those writes are bouncing to somewhere they’re not supposed to, I could be wiping out something the games actually need to run correctly, hence the issues.

Re: Mario Clash: Thanks! Yeah, it seemed to me like if the game had been released with saving, they never would have given you 40 levels to select from right at the start. That seems like a feature that exists purely because the game doesn’t save. In a world where the game did have saving back on release, I think it would absolutely be like the way I patched it, where you can only play levels you’ve previously reached. If I can get that save fixed up I really feel like that will be the definitive way to play Mario Clash (once you’ve also applied DogP’s button-swap patch).

I talked to KR155E on the Discord about this, and apparently on retail releases/flash carts, only the high bytes in SRAM are accessible (as in, you have to read/write only the even bytes, the odd bytes are not valid).

Taking this into account, the likely reason for Red Alarm crashing was that it was trying to read in the depth values before displaying the intro, and it was only getting half of the bytes off the SRAM. With this info in hand, I’ve made a version of the Red Alarm patch which only reads/writes from the high bytes which I’ve attached to this post. Fingers crossed, this means it will work on hardware and I can start switching the rest over to only reading/writing single bytes at a time.

(Also why is the Virtual Boy like this, this is incredibly inconvenient.)