O'Reilly Hacks
oreilly.comO'Reilly NetworkSafari BookshelfConferences Sign In/My Account | View Cart   
Book List Learning Lab PDFs O'Reilly Gear Newsletters Press Room Jobs  

Buy the book!
Gaming Hacks
By Simon Carless
October 2004
More Info

Hack the Dreamcast Visual Memory Unit
Play homebrew games on Dreamcast's LCD-toting memory card
[Discuss (0) | Link to this hack]

One of the more unique aspects of the Sega Dreamcast is the visual memory unit, a 128-KB memory card with a 48 32 resolution LCD monochrome screen. The VMU has clever uses for memory card management (you can manipulate and delete saves without plugging it into a Dreamcast and even connect two memory cards to trade saves), but we're really interested in it for its ability to store games. It comes with a battery and built-in controls (a D-pad minicontroller and two buttons), so you can play standalone games using it, even though it normally plugs into your Dreamcast controller.

Basically, the device resembles a teeny tiny Nintendo Game Boy. As such, it's eminently hackable.

Arming Your VMU

Transferring files from your PC to your Dreamcast may not be exactly straightforward. You have several possible choices:

Hop online

The advantage of this method is that you don't need to burn CDs to manipulate VMU games. A major disadvantage is that you'll need to take your Dreamcast online somehow, which probably means you need a dial-up ISP or an ultra-expensive Dreamcast broadband adaptor.

XDP for fun and VMU profit

A simple if dubious method for acquiring VMU saves is to burn a disc of the XDP Standalone utilities and web browser package from the Psilocybin Dreams site (http://www.psilocybindreams.com).

Click one of the browser options to reach the main menu, then use the digital controller to choose the Menu option. Finally, choose the VMU Mini Games option to see a web page (as if you were actually online) that includes over 30 freeware, freely distributable VMU games. This includes the vast majority of the games we'll talk about in the next section. However, the disc also contains highly customized versions of Dreamcast browser software that, while possibly being abandonware in some abstract sense, the developers may not have permission to distribute. Bear this in mind before downloading.

This solution works because the developers burned an offline web page and a web browser onto the same disc, so it's a little like you're online.

VMU copy

While this option is excellent if you have normal Dreamcast save games that you'd like to transfer to your Dreamcast without going online and grabbing them, there's currently no functionality to detect if a save is actually a VMU game, so VMU game support is broken. Perhaps this will change in the future, though.

VMU Development Resources

Do you think you're a hardcore programmer capable of creating your own VMU games from scratch? It's definitely possible, but it won't be easy. Start with the VMU Development page at http://www.maushammer.com/vmu.html.

This site provides info on a VMU assembler, available in Windows, Linux, and even Amiga (!) flavors. However, VMU development has poor documentation and requires assembly code, so it's hardly straightforward. Also bear in mind that some of the interest in the Dreamcast VMU scene started to die out when the DC began to fade, so many of these pages have fallen into disarray in recent years.

To aid you in your programming task, and heck, even to run the previously mentioned VMU games on your PC as a test, download a PC emulator that claims to emulate the VMU. This should be handy if you want to check ongoing development. However, both the Windows-based VMU emulators, DirectVMS (http://www.dcemulation.com/emu-directvms.htm) and SoftVMS (http://www.dcemulation.com/emu-softvms.htm), seem to crash with some regularity on the most recent versions of Windows. You may have better luck with a Mac OS port of SoftVMS (http://www.bannister.org/software/softvms.htm).

Finally, if you want to know anything else about the VMU, the VMU FAQ at http://rvmu.maushammer.com/faq.html is an extremely useful document that explains many common problems, from how to reset your VMU to animation constraints. However, please bear in mind that its writing preceded the discovery of self-booting methods for burning Dreamcast-compatible CDs, so it doesn't cover any of the self-boot options for running VMUs.

Choosing the Best VMU Games

After you've successfully downloaded a VMU game onto your memory card, you can access it by removing your memory card from its berth in the Dreamcast controller. Press the Mode button on the controller until the playing-card icon flashes, then press the A button to enter the VMU game.

Please note that you can have only one VMU game on your memory card at a time, although you can also store multiple Dreamcast non-minigame saves. The VMU has no multiboot concept; you can't select between multiple games. VMU games may use up to 128 blocks (the official maximum), so you also need to ensure you have enough space, even if the new VMU game writes over the old one.

However, separating the quality games from the mere demos can be tricky when it comes to playable VMU titles. Frankly, it's fun to download everything because the entire VMU pantheon is limited to tens of titles. You can make your own decisions then. If you'd like to do that, you might want to check out the following:

Rockin B's VMU page

This excellent page has quality ratings for each title, with careful picks and even screenshots of the better VMU titles. Because there's no concept of copy protection for VMU titles, it's very clear which are commercial and which are noncommercial VMU games. This page has no commercial VMU titles. See http://www.rockin-b.de/vm/VM-downloads.htm.

PlanetWeb's VMU site

The people behind the PlanetWeb browser for the Dreamcast still have their page up. It includes a few VMU minigames and massive amounts of VMU animations and normal Dreamcast save games, in conjunction with the fan site Booyaka. Visit http://dreamcast.planetweb.com/vmu/.

DCEmulation's VMU Games

Although it lumps everything together, this resource has some interesting VMU games of various kinds, from the sublime to the ridiculous. Learn more at http://www.dcemulation.com/covers/index.cgi?browse&Vmu%20Games.

If I had to pick some homebrew VMU games you should check out because they're wacky, weird, cool, or any of the above, they'd be the following:

Alien Fighter by Soren Gust

This is an excellent vertically scrolling shooter with sound, a saved high score, addictive old-school gameplay, and all the bells and whistles that come with low-resolution black-and-white VMU fun!

Glucky Labyrinth by Omar Cornut

This game is a fine attempt at a DOOM-style 3D maze game, with chests to open, levels to ascend, and smooth-scrolling 3D dungeons to traverse—impressive on such a limited piece of hardware.

Snaky by Anonymous

This classic game featuring the snake with the ever extending tail that the player mustn't bump into, is fairly straightforward but still plenty of fun. It also features a high-score table for your greatest slithers.

Minesweeper by Soren Gust

You all probably know and have suffered inadvisable addictions to the Minesweeper-style game. This is an excellent version, complete with both sound and save games.

You can download these and others (shown in ) from the Rockin B site.

Figure 1. Title screens

O'Reilly Home | Privacy Policy

© 2007 O'Reilly Media, Inc.
Website: | Customer Service: | Book issues:

All trademarks and registered trademarks appearing on oreilly.com are the property of their respective owners.