VMU SD?

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Roareye
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VMU SD?

Post#1 » Sat Sep 25, 2021 4:21 am

Hey guys.

Just a thought that struck me, but we've had lots of DC controllers by different companies but nobody tries to replicate and/or improve the VMU. I've always wondered why.

I'm aware the DC can only read 200 (or 240) blocks from each card, however there was a 4x memory card where you had a simple switch to give one memory card "four" VMUs in one shell.

If this could be done in a custom VMU with a larger memory (even an 8gb SD card would be a monstrous improvement) then we could essentially save all our necessary VMU data on one VMU, we'd just have to press a button to select a different card (essentially hotswapping VMUs).

On the bottom of the VMU (top if it's plugged into the controller) you would have 4 small buttons. Each button is a series of VMU banks, so you can order your VMUs slightly. Say button 1 are Racers, button 2 are Platformers, button 3 are others and button 4 are VMU games (as an example).

Is there a reason this hasn't been done? I'd certainly buy one.

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XadPT
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Re: VMU SD?

Post#2 » Sat Sep 25, 2021 6:43 am

I had the same idea, I think will be nice

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soniccd123
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Re: VMU SD?

Post#3 » Sat Sep 25, 2021 8:47 am

I've been thinking about this about a year now since my main VMU died. Tried to research how the LM-Bus (the bus between a periferal and the controller) works and it actually shouldn't be so hard to adapt existing projects that emulate VMUs like the mrneo adapter or the Pi nano Pop'n music controller. All these projects have other scopes and emulate the VMU as a side project, but as the LM-Bus is just a 4 wire implementation of the MAPLE Bus, should be easy to use what they already achieved in the LM-Bus. I've tried taking a look at the Pop'n Music project as it is open source, unfortunately because of real life time constraints and not having the necessary tools to debug it at home, I have not tried anything

If someone want to take a look, it is a very cool project: https://github.com/charcole/Dreamcast-PopnMusic

Note that having access to the LM-Bus would open a lot of other possibilities to making periferals for the DC, emulating existing ones like the Microphone or simply the rumble pack or even creating new ones.

TapamN
letterbomb
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Re: VMU SD?

Post#4 » Sun Sep 26, 2021 5:47 pm

It should be fairly easy to see how games react to large VMUs by modifying an emulator.

The file allocation table used on VMUs maxes out at 2^16 blocks, so there would be a hard limit of 32 megabytes, but it could be lower depending on how Sega coded the VMU driver.

Even if it's not possible to create VMUs larger than 128KB, adding a bankswap command to the VMU that a loader like GDMenu or DreamShell can run before starting the game would be valuable.

Motoracer5
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Re: VMU SD?

Post#5 » Sun Sep 26, 2021 9:16 pm

Definitely wouldn't need a 8gb card, unless my math is wrong that would be 62500 VMUs worth of storage. Would be amazing if something could be integrated with GDEMU or MODE. Loading games and not having to worry about what vmu is in would be awesome.

I have been liking the Wingman SD for save file management. Easy to organize and keep backups on a PC

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Roareye
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Re: VMU SD?

Post#6 » Sun Sep 26, 2021 11:26 pm

Motoracer5 wrote:Definitely wouldn't need a 8gb card, unless my math is wrong that would be 62500 VMUs worth of storage. Would be amazing if something could be integrated with GDEMU or MODE. Loading games and not having to worry about what vmu is in would be awesome.

I have been liking the Wingman SD for save file management. Easy to organize and keep backups on a PC

Only reason I said an 8gb card was because I don't think anywhere makes smaller ones anymore. But having 62500 VMUs would certainly allow for the whole library lol

What sort of integration did you have in mind? A VMU Manager and a VMU Autoloader when you boot a game? How would this digital management work with things like the DC Browsers for dlc, or would the idea be to do all dlc downloads via PC?

Motoracer5
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Re: VMU SD?

Post#7 » Mon Sep 27, 2021 3:26 am

A VMU per game would make things easy and not use much space. Doubt it is possible to save to the storage on a ODE as it was read only with GDROM though. I think someone made a device that can have 16 VMUs, might have been in megavolt85's maple adapter thread. I actually get by fine with 2 Wingman SD with 240 blocks each.

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fraggle200
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Re: VMU SD?

Post#8 » Mon Sep 27, 2021 4:03 am

seems mad in this day and age that there wasn't an SD solution already. It only dawned on me when 8bitmods brought out the MemCard Pro for the PS1. https://8bitmods.com/memcard-pro-for-pl ... ssic-grey/ that more or less does everything that a 21st century VMU wishlist would have. just a pity it's not for the DC but it's a very good jumping off place to see what's achievable with modern tech. As far as I know, 8bit mods aren't doing something like this for the DC.

Motoracer5
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Re: VMU SD?

Post#9 » Mon Sep 27, 2021 11:43 am

Ahh, that's cool. Too bad there isn't as much market demand for Dreamcast stuff. Probably also more difficult to make something like that for the Dreamcast as the memory card plugs into the controller. Would be awesome though. I surprised it works with an ODE like that, thought it was a bit of a pipe dream when I said it.

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